Add X-KDE-ParentApp entries in metadata.desktop
Summary:
If this entry is not added, kpackagetool5 tries to load the specific
packagestructure plugin, fails to load it and then writes the metainfo
as it is "application" instead of add-on
Reviewers: apol, ngraham
Reviewed By: ngraham
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D21991