OpenAPI Skill server-url configurations

[teresaqhoang]

Motivation and Context

1. Add default parameter values for available functions on Plan creation (ActionPlanner)

• This commit changes the PopulateList function to include the default value of each parameter in the generated string. This makes the list of available functions more informative and helpful for LLM to know the default behavior of a function. The default value is shown in parentheses after the parameter description.

• This is helpful in parsing the correct server-url for OpenAPI functions (before, the planner was suggesting arbitrary values that were more-than-intermittently wrong).

2. Add support to override the server-url from user input

• User input is passed as customer variable in Ask context when SK is invoked in the format {openApiSkillName}-server-url
• This can then be parsed in the SemanticKernelController and passed to the Import method
  i.e.,

if (openApiSkillsAuthHeaders.JiraAuthentication != null)
        {
            this._logger.LogInformation("Registering Jira Skill");
            var authenticationProvider = new BasicAuthenticationProvider(() => { return Task.FromResult(openApiSkillsAuthHeaders.JiraAuthentication); });
            var hasServerUrlOverride = variables.Get("jira-server-url", out string serverUrlOverride);

            await planner.Kernel.ImportOpenApiSkillFromFileAsync(
                skillName: "JiraSkill",
                filePath: Path.Combine(System.IO.Directory.GetCurrentDirectory(), @"Skills/OpenApiSkills/JiraSkill/openapi.json"),
                authCallback: authenticationProvider.AuthenticateRequestAsync,
                serverUrlOverride: hasServerUrlOverride ? serverUrlOverride : null
                );
        }

3. Adds missing user-agent parameter to all ImportOpenApiSkill methods for consistency