Add config parameter to /completion and /chat endpoints

[nikazzio]

This PR adds a new config parameter to customizable LLM configurations in both completion and chat endpoints. The changes include:

• Adding a new config field in ChatBody, CompletionBody, CompletionParams, and ChatParams.
• Updating chain functions in query.py and completions.py to check for and use the provided configuration.

[Copilot]

Pull Request Overview

This PR adds a new config parameter to customizable LLM configurations for both completion and chat endpoints.

• Adds a config field to ChatBody and CompletionBody.
• Refactors chain functions and LLM configuration handling to use get_model_config.
• Introduces tests for the new get_model_config function.

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/test_completions.py	Added tests for get_model_config functionality
brevia/routers/qa_router.py	Added config field to ChatBody
brevia/routers/completion_router.py	Added config field to CompletionBody
brevia/query.py	Updated LLM configuration retrieval to use get_model_config
brevia/models.py	Introduced get_model_config and added glom support
brevia/completions.py	Updated simple_completion_chain to use get_model_config

Comments suppressed due to low confidence (1)

brevia/models.py:51

• The get_settings function is used without being imported. Please add 'from brevia.settings import get_settings' at the top of the file to ensure it is available.

    settings = get_settings()