Don't show "Open With" menu items for empty directories
Any app that registers itself as able to open directories generally can't do anything
useful with an empty directory. So, don't show the Open With menu items for them.
The Open With items still appear for non-empty directories.
Reviewers: Dolphin, elvisangelaccio
Reviewed By: Dolphin, elvisangelaccio
Subscribers: trmdi, kfm-devel
Differential Revision: https://phabricator.kde.org/D20396