[Python] Conversation summary skill porting part I

[poweihuang0817]

Motivation and Context

Porting conversation summary skill. Integration test is added as well. Action item and topic will be ported later.

Contribution Checklist

• [-] The code builds clean without any errors or warnings
• [-] The PR follows SK Contribution Guidelines (https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
• [-] The code follows the .NET coding conventions (https://learn.microsoft.com/dotnet/csharp/fundamentals/coding-style/coding-conventions) verified with dotnet format
• [-] All unit tests pass, and I have added new tests where possible
• [-] I didn't break anyone :smile: