Abstract output dpms handling
Summary:
Move init and Wayland side changes of dpms modes into
AbstractOutput.
Reviewers: KWin, davidedmundson
Reviewed By: KWin, davidedmundson
Subscribers: davidedmundson, kwin
Tags: KWin
Maniphest Tasks: T10016
Differential Revision: https://phabricator.kde.org/D16787