Use QScreen to monitor screen geometry changes

Summary:
TabletDaemon now sets up connections between signals for added, removed,
resized or rotated screens and TabletHandler
TabletHandler now calls mapTabletToCurrentScreenSpace for all screen
geometry changes, not just rotation
Remove rotation tracking code from Xlib and XCB implementations of
X11EventNotifier
Use dbgWacom in TabletFinder
Log logics behind applied mappings in XinputAdaptor

Reviewers: rempt, abrahams, xuetianweng

Reviewed By: xuetianweng

Differential Revision: https://phabricator.kde.org/D7338