.Net: Update to the latest MCP sdk (#12319)

Author: SergeyMenshykh

dotnet/Directory.Packages.props

@@ -68,7 +68,7 @@
     <PackageVersion Include="Microsoft.ML.OnnxRuntime" Version="1.21.0" />
     <PackageVersion Include="Microsoft.ML.Tokenizers.Data.Cl100kBase" Version="1.0.1" />
     <PackageVersion Include="Microsoft.VisualStudio.Threading" Version="17.12.19" />
-    <PackageVersion Include="ModelContextProtocol" Version="0.2.0-preview.1" />
+    <PackageVersion Include="ModelContextProtocol" Version="0.2.0-preview.2" />
     <PackageVersion Include="MSTest.TestFramework" Version="3.8.0" />
     <PackageVersion Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageVersion Include="Npgsql" Version="8.0.6" />

dotnet/src/SemanticKernel.Core/Memory/AIContextExtensions.cs

@@ -21,6 +21,9 @@ public static class AIContextExtensions
     /// <param name="pluginName">The name to give to the plugin.</param>
     public static void AddFromAIContext(this ICollection<KernelPlugin> plugins, AIContext aiContext, string pluginName)
     {
-        plugins.AddFromFunctions(pluginName, aiContext.AIFunctions.Select(x => x.AsKernelFunction()));
+        if (aiContext.AIFunctions is { Count: > 0 })
+        {
+            plugins.AddFromFunctions(pluginName, aiContext.AIFunctions.Select(x => x.AsKernelFunction()));
+        }
     }
 }