Handle multiple providers/llms

[mbertrand]

What are the relevant tickets?

Closes https://github.com/mitodl/hq/issues/6622

Description (What does it do?)

• Adds the langchain-community library and uses the ChatLiteLLM class for all LLM models.
• Updates the LiteLLMProxy default kwargs to work with this class.
• Adds support for one bedrock anthropic model in the LiteLLM proxy server configuration.
• Sets different configurable default models for each bot.

How can this be tested?

• You'll need this env value set (same as heroku mit-learn RC) in backend.local.env : OPENAI_API_KEY
• Start the containers and go to http://ai.open.odl.local:8003. Ask some questions, it should work. Look at the logs, you should find this:

  web-1         | LiteLLM completion() model= gpt-4o; provider = openai

• Add AI_DEFAULT_RECOMMENDATION_MODEL=openai/o3-mini to your backend.local.env file and restart containers.
• Try the chat UI again. It should still work and you should see this in the logs:

  web-1         | LiteLLM completion() model= o3-mini; provider = openai

• Add the following env settings to backend.local.env:

  AI_PROXY_URL=http://litellm:4000
  AI_PROXY_AUTH_TOKEN=sk-secret
  LITELLM_MASTER_KEY=sk-secret
  LITELLM_PROXY_API_KEY
  AI_PROXY_CLASS=LiteLLMProxy
  

• Restart containers and interact with the chatbot again. It should still work and logs should indicate that the requests are going to the LiteLLM proxy service:

    litellm-1     | LiteLLM completion() model= o3-mini; provider = openai
  

[mbertrand]

Will be required for AWS Bedrock models

[mbertrand]

Required for AWS Bedrock models

[mbertrand]

Pydantic warnings coming from ChatLiteLLM class

[mbertrand]

The new o3-mini model does not support the temperature parameter and will raise an exception if it is passed along