Move handling of rotation changes from event handler to screen

Move handling of rotation changes from event handler to screen

Have the navigator event handler emit the new rotation as a signal argument
and let the screen class handle all parts of the change, i.e. also notifying
the window system about the geometry change.

This also allows to rotate all screens, not just the primary screen, if this
should be necessary.

Change-Id: I304a80232b84d2d9130e38e955d5a75b1ccad775
Reviewed-by: Thomas McGuire <thomas.mcguire@kdab.com>
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>