using the qml url interceptor, rewrite imports in order
to load always the plasma styled qqc2 controls in plasmoids
and plasma views. As is per-engine, is possible to load
controls with qstyle theme in configuration dialogs
and plasma style in plasmoids.
Note: this replaces just the style org.kde.desktop
to Plasma and not every style (so with Material
set as QT_QUICK_CONTROLS_STYLE environment variable
plasma would load controls with material style) because
we can control both org.kde.desktop and Plasma styles:
they must have the same subdirectories as unlike files,
their existence is checked before the rewrite (in our case,
"private"), so in order to work they must exist in both
styles