The extension of PromptExecutionSettings is not only for ChatCompletion, but also for text completion and text embedding.

- Updated LLamaSharpChatCompletion class in LLama.SemanticKernel/ChatCompletion/LLamaSharpChatCompletion.cs
  - Changed the type of the "_model" field from "StatelessExecutor" to "ILLamaExecutor"
  - Updated the constructor to accept an "ILLamaExecutor" parameter instead of a "StatelessExecutor" parameter
- Updated LLamaSharpChatCompletion class in LLama.SemanticKernel/LLamaSharp.SemanticKernel.csproj

- Updated LLama.Unittest project in LLama.Unittest/LLama.Unittest.csproj
  - Added a "PackageReference" for "Moq" version 4.20.70
- Added ExtensionMethodsTests class in LLama.Unittest/SemanticKernel/ExtensionMethodsTests.cs
  - Added tests for the "ToLLamaSharpChatHistory" and "ToLLamaSharpInferenceParams" extension methods
- Added LLamaSharpChatCompletionTests class in LLama.Unittest/SemanticKernel/LLamaSharpChatCompletionTests.cs
  - Added tests for the LLamaSharpChatCompletion class

ℹ️ The LLamaSharpChatCompletion class in the LLama.SemanticKernel project has been updated to use the ILLamaExecutor interface instead of the StatelessExecutor class. This change allows for better abstraction and flexibility in the implementation of the LLamaSharpChatCompletion class. The LLamaSharpChatCompletion class is responsible for providing chat completion functionality in the LLamaSharp project. The LLama.Unittest project has also been updated to include tests for the LLamaSharpChatCompletion class and the extension methods used by the class.