This makes KWin switch to in-tree copy of KWaylandServer codebase.
KWaylandServer namespace has been left as is. It will be addressed later
by renaming classes in order to fit in the KWin namespace.
Framework style build system which generates two libraries:
* KF5WaylandClient
* KF5WaylandServer
autotests are adjusted to compile again. They need to be changed to
use the libraries once the export header gets generated.
