Implement the tablet wayland protocol in kwin
Summary:
Uses the tablet classes introduced in kwayland.
Depends on D26858
Test Plan:
Scratched my tablet with a magic stick and it did things depending on the pressure.
https://youtu.be/GGx0TlNJlzs
Reviewers: KWin, Plasma, zzag, davidedmundson
Reviewed By: KWin, Plasma, zzag, davidedmundson
Subscribers: davidedmundson, zzag, kwin
Tags: KWin
Differential Revision: https://phabricator.kde.org/D26859