MSCZ files listed as "MuseScore compressed backup score" in Linux file managers

Describe the bug
On Linux Debian at least, MuseScore files get listed as "MuseScore compressed backup score" in file managers, including the file dialogs within MuseScore, due to a wrong MIME type setting

To Reproduce
Steps to reproduce the behavior:

1. In MuseScore, File / Open
2. Navigate if necessary to a folder containing MSCZ files
3. See error: all MSCZ files listed as "MuseScore compressed backup score"

Expected behavior
File type should say "MuseScore score"

Screenshots

Platform information

• OS: Linux

Additional context
The problem appears to be incorrect info in the MIME type definition:

https://github.com/musescore/MuseScore/blob/master/build/Linux%2BBSD/musescore.xml.in

Both ".mscz" and ".mscz," (with comma) are givne the same MIME type: "x-musescore". Similarly for ".mscx" and ".mscx," which both get "x-musescore+xml". Apaprently, at least some implementations of MIME don't allow multiple entries within the same file to have the same MIME type, and the last one wins.

I think the solution is probably to change the MIME type of the backups to be "x-musescore-backup" and "x-musescore-backup+xml" or something like that. Or maybe someone more expert in MIME can comment or suggest a better solution. But I can confirm that making this change locally on my system fixes it for me.

Inspect build/Linux+B​​SD/musescore.xml.in, focusing on the MIME registrations for *.mscz, *.mscz,, *.mscx, and *.mscx,. Reproduce the label in a Linux file manager or MuseScore's File/Open dialog, then verify that score files are labeled "MuseScore score" and backup files use an appropriate distinct type.