[Bug]: Azure AI Model Inference (not Azure OpenAI) models do not work in GraphRAG

[yueqianh]

@pholz I've been testing other models in Azure AI Foundry. I realised that while DeepSeek-R1 works fine, other models will not work due to the different API endpoint format.

base_url in OpenAI Chat mode:

• DeepSeek-R1: https://[DeepSeek-R1-deploymentname].eastus2.models.ai.azure.com/v1/
• Phi-4 and other models: https://[deployment_name].services.ai.azure.com/models/

GraphRAG auto completes the base_url into the following:

• DeepSeek-R1: https://[DeepSeek-R1-deploymentname].eastus2.models.ai.azure.com/v1/chat/completions
  which is the correct endpoint for accessing DeepSeek-R1 models (no API version)
• Phi-4 and other models: https://[deployment_name].services.ai.azure.com/models/chat/completions
  which lacks the API version query string required for these models. The full endpoint should be: https://[deployment_name].services.ai.azure.com/models/chat/completions?2024-05-01-preview

Seeking help from the GraphRAG team to add support for these Azure AI Model Inference models. Appreciate any workaround!

Originally posted by @yueqianh in #1678