Sync set/send/update methods

Summary:
Currently whenever a single client binds we would incorrectly send an
EDID/uuid/enabled update to every client.

This syncs every property into following the same set/send/update
pattern everywhere.

Test Plan: Existing unit tests

Reviewers: #kwin, romangg

Reviewed By: #kwin, romangg

Subscribers: romangg, kde-frameworks-devel

Tags: #frameworks

Differential Revision: https://phabricator.kde.org/D14505