[Feat] Multi model support (#931)

* Update Llama class to handle chat_format & caching

* Add settings.py

* Add util.py & update __main__.py

* multimodel

* update settings.py

* cleanup

* delete util.py

* Fix /v1/models endpoint

* MultiLlama now iterable, app check-alive on "/"

* instant model init if file is given

* backward compability

* revert model param mandatory

* fix error

* handle individual model config json

* refactor

* revert chathandler/clip_model changes

* handle chat_handler in MulitLlama()

* split settings into server/llama

* reduce global vars

* Update LlamaProxy to handle config files

* Add free method to LlamaProxy

* update arg parsers & install server alias

* refactor cache settings

* change server executable name

* better var name

* whitespace

* Revert "whitespace"

This reverts commit bc5cf51c64a95bfc9926e1bc58166059711a1cd8.

* remove exe_name

* Fix merge bugs

* Fix type annotations

* Fix type annotations

* Fix uvicorn app factory

* Fix settings

* Refactor server

* Remove formatting fix

* Format

* Use default model if not found in model settings

* Fix

* Cleanup

* Fix

* Fix

* Remove unnused CommandLineSettings

* Cleanup

* Support default name for copilot-codex models

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Co-authored-by: Andrei Betlen <abetlen@gmail.com>