Fixing Mistral Templates

[pandora-s-git]

Hi there, fixing the templates as close as possible to the ground truth, you ca find more information regarding the templates in here: https://github.com/mistralai/cookbook/blob/main/concept-deep-dive/tokenization/chat_templates.md

Still not finished yet, so please dont merge yet!

Since it seems the webui uses Jinja, I will base myself on the ones for Hugging Face and customise it depending on the needs for this project!

I will notify once this PR is ready, for now im just experimenting.

Checklist:

• [x] I have read the Contributing guidelines.