Allow terminating or killing root processes by using Polkit

[tsujan]

Sometimes, a root/non-user process may hang and it'll be good if Qps can kill it, as other well-known process managers can.

I'm sure Polkit can be used for this purpose without becoming a build dependency (have used it elsewhere) but I don't know if the implementation will be easy with the untidy code Qps has. Perhaps it could be done after heavy code cleanups.

[stefonarch]

after heavy code cleanups

Yeah, I noticed this 2k line file...
Some translations refer to things never implemented or not working and not shown (Help) .
In weblate/qps I've implemented the "source string browser" (in the panel on the right) - users can open directly the code referring to the actual translation.