convert : improve Mistral models integration (#14737)

* Improve Mistral models integration with llama.cpp

* Revert changes and fix gguf

* Revert change

* refactor convert_mistral_to_gguf.py in convert_hf_to_gguf.py

* Revert collateral

* Rename model name

* refactor

* revert

* remove duplicate

* Remove duplication code

* Fixes

* Fix flake issues

* Apply comments

* Apply comments

* Apply comments

* Fix remote

* add default chat template

* Revert

* nit

Author: juliendenize