feat: Implement structured output by using outlines

[Appointat]

This PR introduces structured output capabilities for both open-source and closed-source language models (LLMs) in our system:

1. Open-source LLMs:

   • Implemented a schema model to integrate open-source, self-hostable LLMs supported by Outlines
   • This enables structured output for open-source models
   • Currently supports platforms: Transformers, LlamaCpp, and vLLM

2. Closed-source LLMs with function calling:

   • Utilized Pydantic to pass expected output structures
   • This approach enables structured output for closed-source models that support function calling

Key changes:

• Added SchemaModel class for open-source LLM integration
• Implemented platform-specific adapters for Transformers, LlamaCpp, and vLLM
• Created PydanticOutputParser for closed-source LLMs with function calling support

Testing:

• Added unit tests for SchemaModel and PydanticOutputParser

Next steps:

• Expand support for additional open-source LLM platforms
• For the closed llms, we will optimize the issue of multi-functions calling at the same time.
• Better ci/cd for the self-hosted models