Undo uploading translations using the "Replace existing translation file" file upload mode

[philipp-kern]

Describe the problem

When using the function to import whole translation files with the replace option set (https://docs.weblate.org/en/weblate-5.14.3/user/files.html#import-methods), as the documentation states, this replaces the whole translation with what is in the uploaded file.

If somebody decides to use this, not reading the documentation or help text and thinking they could update only their existing translations in the file, this would have an disastrous impact.
Because all translations are gone, and when restoring from backup .po files, the approval state as well as all comments, explanations, screenshots and history are missing.

Solution brainstorm

Add an undo action for any uploaded files. Any translations changed/added after the upload need to be either undone as well or the user could be asked about them individually.

Describe alternatives you have considered

Restore from backup.

Screenshots

No response

Additional context

This would be a safety feature for recovery - not sure how often this has happened in the wild.

[nijel]

What might help here is keeping the removed strings around as described in #1993. But I'm still not sure if this is a good idea.