[wayland] Implement maximize rules

Summary:
There is still one small issue that has to be addressed in the future:
xdg-toplevel doesn't have states like MAXIMIZED_VERT or MAXIMIZED_HORZ,
thus Window Rules KCM should display only single maximize rule(not two)
for wayland clients.

Test Plan: The new tests pass.

Reviewers: #kwin, davidedmundson

Reviewed By: #kwin, davidedmundson

Subscribers: kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D19414