Handle Wayland change sets in AbstractOutput

Summary:
Move Wayland change set handling to AbstractOutput and create
virtual functions to call into the hardware implementation

Reviewers: #kwin, davidedmundson

Reviewed By: #kwin, davidedmundson

Subscribers: kwin

Tags: #kwin

Maniphest Tasks: T10016

Differential Revision: https://phabricator.kde.org/D16785