Option to translate the IMAP special folders in the sidebar

Checklist

• I have used the search function to see if someone else has already submitted the same feature request.
• I will describe the problem with as much detail as possible.
• This issue only contains a request for one single feature, not multiple (related) features.

App version

6.509

Problem you are trying to solve

Currently, the IMAP special folders (Archive, Deleted, Drafts, Junk, Sent) are not translated into the app language. I honestly think this is a design error:

1. It assumes that anyone is able to understand the English names for those folders.
2. The Folder settings insinuate that the translations are to be used, only to show the folders untranslated in the sidebar. This is very confusing.
3. It is already abundantly clear what IMAP folder is actually used for the special folder inside the folder settings: they are explicitly mentioned when Automatic is chosen. As such, there is no harm to use the translated names in the sidebar.

I just had a family member come to me in a panic, thinking they might have lost a long email they had just sent. I reckon this is definitely not the first time that would have happened due to this design choice.

What's more, imho it doesn't look tidy at all, and in the ensuing confusion, my first reaction was actually to check on Transifex if the translations were complete.

Related issues (this problem is mentioned, but it is not the core issue there): https://github.com/thundernest/k-9/issues/4300#issuecomment-564115499 and https://github.com/thundernest/k-9/issues/3449#issuecomment-781264989

Suggested solution

Use the app translations for the special folder in the sidebar.

Screenshots / Drawings / Technical details

No response