A new service type is introduced which is used by the KCM to find
all available window switcher layouts. This makes it finally possible
to have 3rd party window switchers.
Also the tabbox finds the packaged QML file through the service
definitions.
Desktop switcher is not yet in packaged version (UI to configure
is missing).
REVIEW: 103951
All the default layouts (informative, compact, text, small and big icons)
are rewritten in QML and replace the ListView used before. The old code
is still around for the desktop switching modes which are not yet ported.
Next steps include to update the configuration module to not show now
obsoleted settings as well as providing a better way to choose the layout.
REVIEW: 102948
