qml app no longer resizes root rectangle in qds

The new QML app used in qds live preview does not re-scale the root rectangle to the window size.

Hello world app using Qt5 kit and qmlscene will re-scale the root rectangle automatically, required for responsive design using anchors.

Hello world app using Qt6 kit and new qml app keeps the root rectangle at the defined size so anchors to the root item have no effect and responsive design is not possible.