Add support for Mistral OCR

[Mistic92]

Mistral just dropped probably best OCR model with support for multilang documents. Would be great to have an option to use it as OCR engine.

https://mistral.ai/news/mistral-ocr
https://docs.mistral.ai/capabilities/document/
https://x.com/sophiamyang/status/1897713370029068381?t=i9lqiApStu9_ag34cn5XeQ&s=19