Add Tongyi Provider Support

[NewToolAI]

Integrate Tongyi provider into the Python package:

• Implement the TongyiProvider class in aisuite/providers/tongyi_provider.py, utilizing the dashscope library.
• Add test cases for the TongyiProvider in tests/client/test_client.py, including mocks for the provider within the tests.
• Provide usage instructions in guides/tongyi.md, detailing how to interact with the Alibaba Tongyi model.

[rohitprasad15]

Thanks for the PR. Please re-test after the addition of pydantic checks in the codebase.
If possible, please add tool calling support as well.
If the model uses OpenAI message format, then you can use Mistral or Together as an example how to use an existing base class to do message conversion.