Make the language switch more intuitive

[teolemon]

Make it clearer that it's not another field, but has impact on all that follows.

[teolemon]

While implementing this, we need to check if the app is able to send several languages, and otherwise, add a warning that the current modifications or any un-uploaded images in the current language will be lost.

[stephanegigandet]

I think we should consider removing the language field in the app completely, and only display/edit in the language of the interface of the app. That will make things much simpler.

[derivator]

only display/edit in the language of the interface of the app.

Lots of reasons why people would use an interface language different than what they're scanning. I think a separate setting would be preferable.