Add response_format parameter support for structured output

[fede-kamel]

Summary

Implements response_format parameter to enable JSON mode and JSON schema output formatting for both Meta Llama and Cohere models. This allows users to leverage structured output capabilities via with_structured_output() and direct response_format configuration.

Changes

• Add response_format field to OCIGenAIBase with comprehensive documentation
• Implement response_format handling in ChatOCIGenAI._prepare_request method
• Support response_format via class initialization, bind(), and model_kwargs
• Add comprehensive unit tests covering all configuration methods
• Add integration tests validating end-to-end functionality with real API calls

Implementation Details

The implementation ensures response_format is properly passed to both GenericChatRequest (Meta Llama) and CohereChatRequest (Cohere) models by adding the parameter to the model_kwargs in the _prepare_request method.

Testing

• Unit Tests: 9/9 tests passing

  • Class-level response_format
  • Response_format via bind()
  • Response_format via model_kwargs
  • Pass-through to API for Generic and Cohere models
  • with_structured_output integration (json_mode and json_schema)

• Integration Tests: 10/10 tests passing with real OCI API calls

  • JSON mode with Meta Llama and Cohere
  • Structured output with Pydantic models
  • JSON schema mode with Meta Llama
  • Complex nested structures

Fixes

Fixes #33

Breaking Changes

None - this is a new feature that is fully backward compatible.