Also send Wayland clients to a new desktop if their desktop was removed
Summary:
So far the method only operated on X11 clients. So when the last desktop
got removed Wayland clients were still on it. As the auto test showed:
this results in a crash.
Credits go to code coverage as it showed that area as red, which made me
look on it and realize this must be broken.
Test Plan: New test case added
Subscribers: plasma-devel, kwin
Tags: KWin
Differential Revision: https://phabricator.kde.org/D8082