* feat(llm_passthrough_endpoints.py): support mistral passthrough
Closes https://github.com/BerriAI/litellm/issues/9051
* feat(llm_passthrough_endpoints.py): initial commit for adding vllm passthrough route
* feat(vllm/common_utils.py): add new vllm model info route
make it possible to use vllm passthrough route via factory function
* fix(llm_passthrough_endpoints.py): add all methods to vllm passthrough route
* fix: fix linting error
* fix: fix linting error
* fix: fix ruff check
* fix(proxy/_types.py): add new passthrough routes
* docs(config_settings.md): add mistral env vars to docs
