Feature request: explicitly tell the user when opening an autosave file instead of the real file, and let the user choose

When the user opens a file, MuseScore always checks whether there is an autosave file for this file.
If there is such an autosave file, MuseScore will open the autosave file instead.

Sometimes this is problematic, namely when the autosave file is corrupted and the real file not. I think that this is what's going on in #18087, because on my computer, where the autosave file for those scores is not present, they open fine, but for the author of that issue they don't.

I think it would be nice if MuseScore at least told the user explicitly when opening an auto-save file instead of a real file, and ideally ask the user about it.

We do have the "Restore session?" dialog, but as I said, opening auto-save files happens not only when restoring a session, but might happen anytime you open a file.

However, the problem isn't very wide-spread; if everything goes well, then auto-save files are automatically deleted when the user closes the file without crashing. But a way to get into a situation where an auto-save file is not deleted, is the following:

1. Open score
2. Open another score in another instance
3. Make changes there
4. Make the instance crash
5. Now, there is an undeleted autosave file for the score from the instance that just crashed
6. Re-open that file
7. It will be opened in a new instance, but that new instance won't ask "Restore session?" because it is a secondary instance (the original instance is namely still running)
8. MuseScore sees that there is an autosave file, so it opens the autosave file instead of the real file. This is (normally) good, because otherwise the changes would have been lost, but I think MuseScore should inform the user about this.