GitHub OpenAPI skill integration with planner (#792)

### Motivation and Context
This PR enables GitHub integration with Copilot Planner. 


### Description
Server-side
- Added C# classes for GitHub schema objects
- Adds tokenLimit for Planner response content. Currently, it's set at
75% of the remaining limit after memories response and document context
have already been allocated.
- Added `OptimizeOpenApiSkillJson` method that is called on Planner
completion. This method:
- removes all new line characters (huge token suck) from API response
- truncates the API response by object until it's under the
relatedInformationTokenLimit.
- If the request can't be truncated, error message added to bot context
- For GitHub skills specifically, the API response is deserialized into
`PullRequest` or `PullRequest[]` objects to filter noisy properties.

Web app side
- If plugins require additional api requirements, these are added to the
ask variables (rather than headers in http request) -- this allows the
kernel/planner to directly consume these without any additional handling
server side
- `repo` and `owner` added as additional GitHub api requirements
- Rename ApiRequirements to ApiProperties. These properties can be
optional.


![image](https://user-images.githubusercontent.com/125500434/236005717-14016432-b5de-47b3-a128-e38418c267e3.png)

samples/apps/copilot-chat-app/webapi/Skills/ChatSkill.cs

@@ -3,6 +3,7 @@
 using System.Globalization;
 using System.Text.Json;
 using System.Text.Json.Nodes;
+using System.Text.RegularExpressions;
 using Microsoft.SemanticKernel;
 using Microsoft.SemanticKernel.AI.TextCompletion;
 using Microsoft.SemanticKernel.Memory;
@@ -11,6 +12,7 @@
 using Microsoft.SemanticKernel.SkillDefinition;
 using SemanticKernel.Service.Config;
 using SemanticKernel.Service.Model;
+using SemanticKernel.Service.Skills.OpenApiSkills;
 using SemanticKernel.Service.Storage;
 
 namespace SemanticKernel.Service.Skills;
@@ -212,27 +214,30 @@ public async Task<string> AcquireExternalInformationAsync(SKContext context)
         if (plan.Steps.Count > 0)
         {
             SKContext planContext = await plan.InvokeAsync(plannerContext);
+            int tokenLimit = int.Parse(context["tokenLimit"], new NumberFormatInfo());
 
             // The result of the plan may be from an OpenAPI skill. Attempt to extract JSON from the response.
             if (!this.TryExtractJsonFromOpenApiPlanResult(planContext.Variables.Input, out string planResult))
             {
                 // If not, use result of the plan execution result directly.
                 planResult = planContext.Variables.Input;
             }
+            else
+            {
+                int relatedInformationTokenLimit = (int)Math.Floor(tokenLimit * this._promptSettings.RelatedInformationContextWeight);
+                planResult = this.OptimizeOpenApiSkillJson(planResult, relatedInformationTokenLimit, plan);
+            }
 
             string informationText = $"[START RELATED INFORMATION]\n{planResult.Trim()}\n[END RELATED INFORMATION]\n";
 
             // Adjust the token limit using the number of tokens in the information text.
-            int tokenLimit = int.Parse(context["tokenLimit"], new NumberFormatInfo());
             tokenLimit -= Utilities.TokenCount(informationText);
             context.Variables.Set("tokenLimit", tokenLimit.ToString(new NumberFormatInfo()));
 
             return informationText;
         }
-        else
-        {
-            return string.Empty;
-        }
+
+        return string.Empty;
     }
 
     /// <summary>
@@ -404,6 +409,83 @@ private bool TryExtractJsonFromOpenApiPlanResult(string openApiSkillResponse, ou
         return false;
     }
 
+    /// <summary>
+    /// Try to optimize json from the planner response
+    /// based on token limit
+    /// </summary>
+    private string OptimizeOpenApiSkillJson(string jsonContent, int tokenLimit, Plan plan)
+    {
+        int jsonTokenLimit = (int)(tokenLimit * this._promptSettings.RelatedInformationContextWeight);
+
+        // Remove all new line characters + leading and trailing white space
+        jsonContent = Regex.Replace(jsonContent.Trim(), @"[\n\r]", string.Empty);
+        var document = JsonDocument.Parse(jsonContent);
+        string lastSkillInvoked = plan.Steps[^1].SkillName;
+
+        // Check if the last skill invoked was GitHubSkill and deserialize the JSON content accordingly
+        if (string.Equals(lastSkillInvoked, "GitHubSkill", StringComparison.Ordinal))
+        {
+            var pullRequestType = document.RootElement.ValueKind == JsonValueKind.Array ? typeof(PullRequest[]) : typeof(PullRequest);
+
+            // Deserializing limits the json content to only the fields defined in the GitHubSkill/Model classes
+            var pullRequest = JsonSerializer.Deserialize(jsonContent, pullRequestType);
+            jsonContent = pullRequest != null ? JsonSerializer.Serialize(pullRequest) : string.Empty;
+            document = JsonDocument.Parse(jsonContent);
+        }
+
+        int jsonContentTokenCount = Utilities.TokenCount(jsonContent);
+
+        // Return the JSON content if it does not exceed the token limit
+        if (jsonContentTokenCount < jsonTokenLimit)
+        {
+            return jsonContent;
+        }
+
+        List<object> itemList = new();
+
+        // Summary (List) Object
+        if (document.RootElement.ValueKind == JsonValueKind.Array)
+        {
+            foreach (JsonElement item in document.RootElement.EnumerateArray())
+            {
+                int itemTokenCount = Utilities.TokenCount(item.ToString());
+
+                if (jsonTokenLimit - itemTokenCount > 0)
+                {
+                    itemList.Add(item);
+                    jsonTokenLimit -= itemTokenCount;
+                }
+                else
+                {
+                    break;
+                }
+            }
+        }
+
+        // Detail Object
+        if (document.RootElement.ValueKind == JsonValueKind.Object)
+        {
+            foreach (JsonProperty property in document.RootElement.EnumerateObject())
+            {
+                int propertyTokenCount = Utilities.TokenCount(property.ToString());
+
+                if (jsonTokenLimit - propertyTokenCount > 0)
+                {
+                    itemList.Add(property);
+                    jsonTokenLimit -= propertyTokenCount;
+                }
+                else
+                {
+                    break;
+                }
+            }
+        }
+
+        return itemList.Count > 0
+            ? JsonSerializer.Serialize(itemList)
+            : String.Format(CultureInfo.InvariantCulture, "JSON response for {0} is too large to be consumed at this time.", lastSkillInvoked);
+    }
+
     /// <summary>
     /// Save a new message to the chat history.
     /// </summary>

samples/apps/copilot-chat-app/webapi/Skills/OpenApiSkills/GitHubSkill/Model/Label.cs

@@ -0,0 +1,40 @@
+using System.Text.Json.Serialization;
+
+namespace SemanticKernel.Service.Skills.OpenApiSkills;
+
+/// <summary>
+/// Represents a pull request label.
+/// </summary>
+public class Label
+{
+    /// <summary>
+    /// Gets or sets the ID of the label.
+    /// </summary>
+    [JsonPropertyName("id")]
+    public long Id { get; set; }
+
+    /// <summary>
+    /// Gets or sets the name of the label.
+    /// </summary>
+    [JsonPropertyName("name")]
+    public string Name { get; set; }
+
+    /// <summary>
+    /// Gets or sets the description of the label.
+    /// </summary>
+    [JsonPropertyName("description")]
+    public string Description { get; set; }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="Label"/> class.
+    /// </summary>
+    /// <param name="id">The ID of the label.</param>
+    /// <param name="name">The name of the label.</param>
+    /// <param name="description">The description of the label.</param>
+    public Label(long id, string name, string description)
+    {
+        this.Id = id;
+        this.Name = name;
+        this.Description = description;
+    }
+}

samples/apps/copilot-chat-app/webapi/Skills/OpenApiSkills/GitHubSkill/Model/PullRequest.cs

@@ -0,0 +1,116 @@
+using System.Text.Json.Serialization;
+
+namespace SemanticKernel.Service.Skills.OpenApiSkills;
+
+/// <summary>
+/// Represents a GitHub Pull Request.
+/// </summary>
+public class PullRequest
+{
+    /// <summary>
+    /// Gets or sets the URL of the pull request
+    /// </summary>
+    [JsonPropertyName("url")]
+    public System.Uri Url { get; set; }
+
+    /// <summary>
+    /// Gets or sets the unique identifier of the pull request
+    /// </summary>
+    [JsonPropertyName("id")]
+    public int Id { get; set; }
+
+    /// <summary>
+    /// Gets or sets the number of the pull request
+    /// </summary>
+    [JsonPropertyName("number")]
+    public int Number { get; set; }
+
+    /// <summary>
+    /// Gets or sets the state of the pull request
+    /// </summary>
+    [JsonPropertyName("state")]
+    public string State { get; set; }
+
+    /// <summary>
+    /// Whether the pull request is locked
+    /// </summary>
+    [JsonPropertyName("locked")]
+    public bool Locked { get; set; }
+
+    /// <summary>
+    /// Gets or sets the title of the pull request
+    /// </summary>
+    [JsonPropertyName("title")]
+    public string Title { get; set; }
+
+    /// <summary>
+    /// Gets or sets the user who created the pull request
+    /// </summary>
+    [JsonPropertyName("user")]
+    public GitHubUser User { get; set; }
+
+    /// <summary>
+    /// Gets or sets the labels associated with the pull request
+    /// </summary>
+    [JsonPropertyName("labels")]
+    public List<Label> Labels { get; set; }
+
+    /// <summary>
+    /// Gets or sets the date and time when the pull request was last updated
+    /// </summary>
+    [JsonPropertyName("updated_at")]
+    public DateTime UpdatedAt { get; set; }
+
+    /// <summary>
+    /// Gets or sets the date and time when the pull request was closed
+    /// </summary>
+    [JsonPropertyName("closed_at")]
+    public DateTime? ClosedAt { get; set; }
+
+    /// <summary>
+    /// Gets or sets the date and time when the pull request was merged
+    /// </summary>
+    [JsonPropertyName("merged_at")]
+    public DateTime? MergedAt { get; set; }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="PullRequest"/> class, representing a pull request on GitHub.
+    /// </summary>
+    /// <param name="url">The URL of the pull request.</param>
+    /// <param name="id">The unique identifier of the pull request.</param>
+    /// <param name="number">The number of the pull request within the repository.</param>
+    /// <param name="state">The state of the pull request, such as "open", "closed", or "merged".</param>
+    /// <param name="locked">A value indicating whether the pull request is locked for comments or changes.</param>
+    /// <param name="title">The title of the pull request.</param>
+    /// <param name="user">The user who created the pull request.</param>
+    /// <param name="labels">A list of labels assigned to the pull request.</param>
+    /// <param name="updatedAt">The date and time when the pull request was last updated.</param>
+    /// <param name="closedAt">The date and time when the pull request was closed, or null if it is not closed.</param>
+    /// <param name="mergedAt">The date and time when the pull request was merged, or null if it is not merged.</param>
+    public PullRequest(
+        System.Uri url,
+        int id,
+        int number,
+        string state,
+        bool locked,
+        string title,
+        GitHubUser user,
+        List<Label> labels,
+        DateTime updatedAt,
+        DateTime? closedAt,
+        DateTime? mergedAt
+    )
+    {
+        this.Url = url;
+        this.Id = id;
+        this.Number = number;
+        this.State = state;
+        this.Locked = locked;
+        this.Title = title;
+        this.User = user;
+        this.Labels = labels;
+        this.UpdatedAt = updatedAt;
+        this.ClosedAt = closedAt;
+        this.MergedAt = mergedAt;
+    }
+}

samples/apps/copilot-chat-app/webapi/Skills/OpenApiSkills/GitHubSkill/Model/Repo.cs

@@ -0,0 +1,33 @@
+using System.Text.Json.Serialization;
+
+namespace SemanticKernel.Service.Skills.OpenApiSkills;
+
+/// <summary>
+/// Represents a GitHub Repo.
+/// </summary>
+public class Repo
+{
+    /// <summary>
+    /// Gets or sets the name of the repo
+    /// </summary>
+    [JsonPropertyName("name")]
+    public string Name { get; set; }
+
+    /// <summary>
+    /// Gets or sets the full name of the repo
+    /// </summary>
+    [JsonPropertyName("full_name")]
+    public string FullName { get; set; }
+
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="Repo"/>.
+    /// </summary>
+    /// <param name="name">The name of the repository, e.g. "dotnet/runtime".</param>
+    /// <param name="fullName">The full name of the repository, e.g. "Microsoft/dotnet/runtime".</param>
+    public Repo(string name, string fullName)
+    {
+        this.Name = name;
+        this.FullName = fullName;
+    }
+}

samples/apps/copilot-chat-app/webapi/Skills/OpenApiSkills/GitHubSkill/Model/User.cs

@@ -0,0 +1,56 @@
+using System.Text.Json.Serialization;
+
+namespace SemanticKernel.Service.Skills.OpenApiSkills;
+
+/// <summary>
+/// Represents a user on GitHub.
+/// </summary>
+public class GitHubUser
+{
+    /// <summary>
+    /// The user's name.
+    /// </summary>
+    [JsonPropertyName("name")]
+    public string Name { get; set; }
+
+    /// <summary>
+    /// The user's email address.
+    /// </summary>
+    [JsonPropertyName("email")]
+    public string Email { get; set; }
+
+    /// <summary>
+    /// The user's numeric ID.
+    /// </summary>
+    [JsonPropertyName("id")]
+    public int Id { get; set; }
+
+    /// <summary>
+    /// The user's type, e.g. User or Organization.
+    /// </summary>
+    [JsonPropertyName("type")]
+    public string Type { get; set; }
+
+    /// <summary>
+    /// Whether the user is a site admin.
+    /// </summary>
+    [JsonPropertyName("site_admin")]
+    public bool SiteAdmin { get; set; }
+
+    /// <summary>
+    /// Creates a new instance of the User class.
+    /// </summary>
+    /// <param name="name">The user's name.</param>
+    /// <param name="email">The user's email address.</param>
+    /// <param name="id">The user's numeric ID.</param>
+    /// <param name="type">The user's type.</param>
+    /// <param name="siteAdmin">Whether the user is a site admin.</param>
+    public GitHubUser(string name, string email, int id, string type, bool siteAdmin)
+    {
+        this.Name = name;
+        this.Email = email;
+        this.Id = id;
+        this.Type = type;
+        this.SiteAdmin = siteAdmin;
+    }
+}

samples/apps/copilot-chat-app/webapi/Skills/PromptSettings.cs

@@ -34,6 +34,13 @@ public PromptSettings(PromptsConfig promptsConfig)
     /// </summary>
     internal double DocumentContextWeight { get; } = 0.3;
 
+    /// <summary>
+    /// Weight of information returned from planner (i.e., responses from OpenAPI skills).
+    /// Percentage calculated from remaining token limit after memories response and document context have already been allocated.
+    /// Contextual prompt excludes all the system commands.
+    /// </summary>
+    internal double RelatedInformationContextWeight { get; } = 0.75;
+
     /// <summary>
     /// Maximum number of tokens per line that will be used to split a document into lines.
     /// Setting this to a low value will result in higher context granularity, but