Use KDesktopFile to parse Solid predicates, rather than KService
These files have Type=Service in them, which KService no longer
accepts in KF6. We could fix them, but then 3rd-party service files
would still be broken in Plasma 6. Not ideal.
Instead, let's use KDesktopFile to parse these files. All we're really
doing with them anyway is looking at the X-KDE-AliasFor, Name, and
Exec keys; we're not making use of anything special that KService
offers. so it still works fine.
Please review carefully, as this is code I'm not super familiar with.
Now actions appear in the expanded view, and all of the actions work when clicked on:
