encode the old appstream id as provided by the new appstream id

Summary:
without this appstream won't be able to know that a query for the old id
'org.kde.krita.desktop' is referring to this component

Reviewers: Krita, rempt

Reviewed By: Krita, rempt

Tags: Krita

Differential Revision: https://phabricator.kde.org/D18036