Fix agents devise FR translations

Created by: Vin0uz

👋 First contribution here

Just added devise generated shared views, and added 🇫🇷 translations. I left all the generated links, some could be cleaned away if not required (model is not lockable for example). I added github in the oauth provider translation list, even though it's not for agents, but this bit could be removed too.

The spec is super-basic, just testing the translation, not testing the reset password functionnality itself. I would push it in another diff but could be piled on this one I guess 🤔

Closes #1140 (closed)

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