Added `backend_options` parameter to llm judges. (#963)
* Added `backend_options` parameter to llm judges.
Currently only used for litellm backend but can be extended to other backends as well. Allows to specify whether to use caching or not, the number of concurrent requests, and whether the token output budget should be increased for reasoning models.
* Implemented changes from code review
* Ran pre-commit hooks
---------
Co-authored-by: Nathan Habib <30601243+NathanHB@users.noreply.github.com>
