Make it possible to support exclusive action groups

Summary:
We need to find away to import 2.3 if available otherwise modelData.Controls.ActionGroup returns null.

CCBUG: 391144

Reviewers: #kirigami, mart

Reviewed By: #kirigami, mart

Subscribers: mart, plasma-devel

Tags: #kirigami

Differential Revision: https://phabricator.kde.org/D10892