Add command option to quit

[thatso]

The problem

As the request for a proper scheduler #1403 does not gain any traction, how about a simple command option to quit Vorta without a GUI prompt instead?

Requested Solution

vorta -q or vorta --quit should gracefully and silently close the application

Additional context

This feature would allow for scheduled backups via cronjobs without having to manually close Vorta afterwards or keep it running in the background and consume ressources (no matter how low they might be).

[m3nu]

How about killall -c vorta after your cron job?

[thatso]

While this might work, I would really prefer a dedicated command option over a sledgehammer-type method.