.Net: Graduate some experimental features (microsoft#6245)

### Motivation and Context

Closes microsoft#6211 

### Description

<!-- Describe your changes, the overall approach, the underlying design.
These notes will help understanding how your code works. Thanks! -->

### Contribution Checklist

<!-- Before submitting this PR, please make sure: -->

- [ ] The code builds clean without any errors or warnings
- [ ] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [ ] All unit tests pass, and I have added new tests where possible
- [ ] I didn't break anyone 😄

dotnet/src/Connectors/Connectors.OpenAI/OpenAIPromptExecutionSettings.cs

@@ -137,7 +137,6 @@ public int ResultsPerPrompt
     /// If specified, the system will make a best effort to sample deterministically such that repeated requests with the
     /// same seed and parameters should return the same result. Determinism is not guaranteed.
     /// </summary>
-    [Experimental("SKEXP0010")]
     [JsonPropertyName("seed")]
     public long? Seed
     {

dotnet/src/SemanticKernel.Abstractions/Functions/KernelFunctionMetadata.cs

@@ -99,7 +99,6 @@ public KernelReturnParameterMetadata ReturnParameter
     }
 
     /// <summary>Gets optional metadata in addition to the named properties already available on this class.</summary>
-    [Experimental("SKEXP0001")]
     public ReadOnlyDictionary<string, object?> AdditionalProperties
     {
         get => this._additionalProperties ??= s_emptyDictionary;

dotnet/src/SemanticKernel.Core/Functions/KernelFunctionFactory.cs

@@ -41,7 +41,6 @@ public static KernelFunction CreateFromMethod(
     /// <param name="method">The method to be represented via the created <see cref="KernelFunction"/>.</param>
     /// <param name="options">Optional function creation options.</param>
     /// <returns>The created <see cref="KernelFunction"/> for invoking <paramref name="method"/>.</returns>
-    [Experimental("SKEXP0001")]
     public static KernelFunction CreateFromMethod(
         Delegate method,
         KernelFunctionFromMethodOptions? options) =>
@@ -77,7 +76,6 @@ public static KernelFunction CreateFromMethod(
     /// <param name="target">The target object for the <paramref name="method"/> if it represents an instance method. This should be null if and only if <paramref name="method"/> is a static method.</param>
     /// <param name="options">Optional function creation options.</param>
     /// <returns>The created <see cref="KernelFunction"/> for invoking <paramref name="method"/>.</returns>
-    [Experimental("SKEXP0001")]
     public static KernelFunction CreateFromMethod(
         MethodInfo method,
         object? target,

dotnet/src/SemanticKernel.Core/Functions/KernelFunctionFromMethodOptions.cs

@@ -4,7 +4,6 @@
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.ComponentModel;
-using System.Diagnostics.CodeAnalysis;
 using System.Reflection;
 using Microsoft.Extensions.Logging;
 
@@ -13,7 +12,6 @@ namespace Microsoft.SemanticKernel;
 /// <summary>
 /// Optional options that can be provided when creating a <see cref="KernelFunction"/> from a method.
 /// </summary>
-[Experimental("SKEXP0001")]
 public sealed class KernelFunctionFromMethodOptions
 {
     /// <summary>