Use own fork of QQuickStyleItem
Summary: use a local copy of qqc1 qquickstyleitem, remove all qqc1 usage
Test Plan: all of kirigami gallery works with the new style
Reviewers: Plasma, davidedmundson
Reviewed By: Plasma, davidedmundson
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D6028