kio slaves aren't desktop applications but generic components

Summary:
https://www.freedesktop.org/software/appstream/docs/chap-Metadata.html#sect-Metadata-GenericComponent
https://www.freedesktop.org/software/appstream/docs/sect-Metadata-Application.html

Reviewers: elvisangelaccio

Reviewed By: elvisangelaccio

Differential Revision: https://phabricator.kde.org/D11186