Put the IM protocol files into a QResource

Summary:
This should address the unit test issues that Allen and Nico reported,
and that the Windows CI also shows. It also makes the test work without
prior installation.

Reviewers: mlaurent, winterz

Reviewed By: mlaurent, winterz

Subscribers: winterz, kde-pim

Tags: KDE PIM

Differential Revision: https://phabricator.kde.org/D21223