feat(wren-ai-service): support multi compnents(llm, embedder, engine, document store) configuration

[paopa]

This pull request introduces several updates and improvements to our codebase:

1. Configuration Management:

   • The system now supports fetching configuration from multiple sources, including environment variables and a new multi-LLM (Language Learning Model) configuration.
   • The existing method of fetching configuration from environment variables is retained to ensure backward compatibility.

2. Deployment Enhancements:

   • The multi-LLM configuration is currently supported only for local deployments.
   • Future plans include extending this support to Docker and Kubernetes deployments once the multi-LLM configuration is deemed stable and mature.

Detailed Description

• Backward Compatibility: We have ensured that the current method of fetching configuration from environment variables remains intact. This allows for a smooth transition and gives us the flexibility to switch to the new multi-LLM configuration gradually.
• Local Deployment: The new multi-LLM configuration is currently enabled only for local deployments. This allows us to test and refine the configuration before rolling it out to more complex deployment environments like Docker and Kubernetes.

Future Plans

• Once the multi-LLM configuration is stable and mature, we plan to:
  • Remove the old method of fetching configuration from environment variables.
  • Update the deployment approach for Docker and Kubernetes to support the new configuration.