wayland: Set kwin up for allowing Xwayland clients scale themselves
Announces that the wayland backend supports the XwaylandClientsScale setting, which is a boolean value to tell kwin whether it should automatically scale xwayland apps or let the apps do it themselves.
When the setting changes:
- Updates and notifies kwin's xwayland scale value so it adapts.
- Runs the fonts kcminit module so that the system gets properly initialised.
Edited by David Edmundson