update for newest AtCore
Summary:
Update Atelier for D13281
- use atcoreMessage
- remove ateliers r/w message since its a atcoreMessage
Reviewers: laysrodrigues, tcanabrava, patrickelectric
Reviewed By: patrickelectric
Subscribers: Atelier: General Development
Tags: Atelier: General Development
Differential Revision: https://phabricator.kde.org/D13282