Bring your own model docs

[mateoperezrivera]

This pull request introduces a new feature that allows users to bring their own models to GPT-RAG, supporting various model providers. The documentation has been updated to include detailed instructions on configuring these models and setting the necessary environment variables.

Key changes include:

Documentation Updates:

• Added a new section in docs/BRING_YOUR_OWN_MODEL.md explaining how to configure and use models from different providers, such as Azure OpenAI, OpenAI, Anthropic, Amazon Bedrock, Google, Vertex, Mistral, Ollama, and Onnx.
• Provided a table listing the required environment variables and constructor settings for each provider, along with their necessity for integration.
• Included guidance on using Key Vault for API key management instead of environment variables for certain providers.

[placerda]

@gbecerra1982 @mateoperezrivera since this is specific to the SK Orchestrator, can we include just a reference to the documentation in that repository? There are other features belonging to the AG Orchestrator where we could do the same. As both orchestrators are expanding and offering different features, this approach will help organize the documentation within their respective repositories. Let's discuss this together.

Another example:
https://github.com/Azure/GPT-RAG/blob/main/docs/GUIDE.md#enabling-multimodality