applets/kicker: provide url in recent apps model

Reason for the change

Kicker's recentusagemodel does not report the url for recent apps, which means that they can't be added to the desktop/panel by drag&drop, which requires the url to the desktop file. Instead, we get an empty QVariant, which mostly just silently fails but with proper setup might add the entry that would be at that point in the recent files list to the panel/desktop instead.

Instead, we take the url from the kservice file, and provide it in the model as usual.

Test plan

Drag an entry from kicker or kickerdash's Recent Applications lists to a panel. (For kickerdash you need to alt-tab out of the dash).

Screenshots or screen recordings

N/A

Bugs fixed

N/A