The example uses QTreeWidget when it should use a QTreeView with a
dedicated item model, primarily shows how to use item views (and very
little about QSettings), and is generally not useful to show how an
application could or should use QSettings to store settings.
Turn it into a manual test instead; it's useful for that as it supports
ini and plist files, and settings in different scopes.
Pick-to: 6.7
Fixes: QTBUG-119978
Change-Id: I7ce039f6391c41c679d126d90a251eee60327c39
Reviewed-by: Ed Cooke <ed.cooke@qt.io>
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>
