Patch MistralCommonTokenizer (#41439)
* Fix token_to_id and add add_generation_prompt
* Fix spm download
* Refactor spm
* Try another possibly non-gated spm
* Improve get_vocab
* lint
* Improve get_vocab
* Add warn to piece_to_id
* Improve from_pretrained raise and revert model spm
* Revert fast
