.Net: Avoid sending duplicate function tools when creating a thread

[markwallace-microsoft]

Motivation and Context

• When create an AzureAIAgent tools can be specified including function tools. These become part of the Agent definition.
• When creating a thread for an AzureAIAgent we are taking KernelFunction's and adding them to the list of tool overrides for the Agent. The Kernel must have all functions that agent can call so it will include function defined when the agent was created. This was leading to an 400 error because the request included duplicate function tools.

  Message: 
    Azure.RequestFailedException : Function tools must have unique names.
    Status: 400 (Bad Request)
    
    Content:
    {
      "error": {
        "message": "Function tools must have unique names.",
        "type": "invalid_request_error",
        "param": "tools[9]",
        "code": null
      }
    }
  

• This PR checks for and eliminates any duplicates.
• This PR also adds a namespace for OpenAI Assistant and Azure AI Agent getting started samples so they are clearly separated in the Visual Studio Test Explorer

Description

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄

[crickman]

Note: I suspect this issue also exists for assistant API. Because we proxy assistant creation, the path isn't quite as available; although, the exact same dynamic could occur if specifying the agent identifier for an assistant created outside of the framework.

[markwallace-microsoft]

Note: I suspect this issue also exists for assistant API. Because we proxy assistant creation, the path isn't quite as available; although, the exact same dynamic could occur if specifying the agent identifier for an assistant created outside of the framework.

This is one of the investigations for the declarative file format specification so I'll test this out.