Summary:
Currently, --about doesn't have any effect. In addition to that, the about
data contains outdated information.

This change hopefully addresses all previously mentioned issues.

Test Plan: Ran kwin_wayland --author.

Reviewers: #kwin, graesslin

Reviewed By: #kwin, graesslin

Subscribers: graesslin, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D17319