Refactor to adopt Microsoft.Extensions.AI. #1 #2 #8 Refactored SemanticTestBase to use ScenarioAssert and IChatClient. Updated KernelChatTests to use ScenarioAssert. Removed obsolete test classes and methods, including FunctionTests and KernelTests. Deleted config.json, sktest.md, and skprompt.txt files. Updated skUnit.Tests.csproj to remove references to deleted files and scenarios. Updated ScenarioAssert_Initialize.cs and SemanticAssert.cs to use IChatClient. Removed PocomoPlugin.cs and related configurations. Updated skUnit.csproj to target .NET 8.0 and updated package references. Added new ChatClientTests class in ChatClientTests.cs. Introduced new methods in ScenarioAssert for chat scenario validation.