Add mount option override checkbox

[samuel-w]

Replaces #522, fixes #520

[codecov-io]

Codecov Report

Merging #682 (5be3279) into master (9a4bbf0) will decrease coverage by 3.18%.
The diff coverage is 83.33%.

@@            Coverage Diff             @@
##           master     #682      +/-   ##
==========================================
- Coverage   73.35%   70.16%   -3.19%     
==========================================
  Files          55       55              
  Lines        3715     3720       +5     
==========================================
- Hits         2725     2610     -115     
- Misses        990     1110     +120     

Impacted Files	Coverage Δ
src/vorta/models.py	80.19% <ø> (-0.50%)	⬇️
src/vorta/borg/mount.py	85.00% <83.33%> (-1.67%)	⬇️
src/vorta/keyring/kwallet.py	0.00% <0.00%> (-57.15%)	⬇️
src/vorta/autostart.py	45.45% <0.00%> (-51.52%)	⬇️
src/vorta/keyring/abc.py	51.42% <0.00%> (-37.15%)	⬇️
src/vorta/keyring/secretstorage.py	0.00% <0.00%> (-36.85%)	⬇️
src/vorta/notifications.py	50.00% <0.00%> (-34.85%)	⬇️
src/vorta/keyring/db.py	66.66% <0.00%> (-33.34%)	⬇️
src/vorta/network_status/abc.py	64.70% <0.00%> (-23.53%)	⬇️
src/vorta/network_status/network_manager.py	64.75% <0.00%> (-9.02%)	⬇️
... and 3 more

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[m3nu]

Minor nitpick: I prefer to have this option in the misc tab. Why?

• I doesn't clutter the archive tab.
• Not used often.
• If it's used, I may use it for multiple profiles (e.g. if I often restore data from NAS backups)
• No need to pass new options around.

[samuel-w]

Seems reasonable.