Install related ref instead attempting to upgrade it

Summary:
When upgrading an app, we attempt to also upgrade related refs, but we
fail if some of the listed refs is not installed. We should check whether
we are trying to upgrade installed ref and if not, then just install it.

Reviewers: apol

Reviewed By: apol

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D8784