Align on person/people vs faces/face terms in languages

[marc7s]

This issue relates to the frontend and the UX, and not the code.

Currently, there is no clear definition of what is considered a person and what is considered a face. There are face groups identified, which are named faces, but they are under the "people" page. We should have a clear definition of what a person is, and what a face is. Maybe one of the terms is enough?

For example, under the "People" page, there is the option to "recognize unlabeled faces", and then to merge/move/detach a face. But when looking at the translations, they do not align with each other. For the danish translation, the page is called "Personer" (People), but the options are "Sammenflet personer" (Merge people) but then "Flyt ansigter" (Move faces) and for some reason "Løsriv billeder" (Detach images). I have noticed things like these among other languages as well, but I don't speak enough languages to be able to confidently provide translations.

So I would propose we define these terms (do we call them people or faces? or both? if so what are people and what are faces?), and maybe start a Wiki for things like these?

Maybe a face is an individual recognized face, and then a face group is called a person? And so the page should still be named People, referring to the multiple persons identified. I think this makes sense and is close to the current standard, however it is not aligned across languages, or even within the same language in some cases at the moment.

From these definitions we can then decide what the page should be called, and what the actions (merge/move/detach) and any other things relating to people should be called. And then update the translations to reflect these definitions.

Context: This issue arose as a question in #912 when adding a feature related to faces.