5.24: taskmanager: Use proper QUrls for recent document actions
The resource can either be a URL or an absolute path, the url() method converts the latter into a proper URL. Without this, a local path might end up getting parsed (badly) as URL, causing weird behaviour later, like resorting to kioexec/kio-fuse.
Plasma/5.24 backport note: Here it doesn't request URLs, so the resource is actually never a valid URL!
BUG: 457685 (cherry picked from commit bf37558f)