[Notifications] Restore fallback to local URL when no place is found
This got removed in d82513ce as I thought a user would always have a "Root" entry, leading to "Root/foo" paths.
However, if you hide a place, it will naturally not be considered for closestItem
resulting in the final QUrl::toDisplayString
being hit, giving us a not so
nice file:///
URL.
Turns out on my laptop I actually have "Root" hidden from my Places panel… so copying to /tmp
gave me file:///tmp
. With this patch I get a nicer /tmp
again.