SensorFaceController: Set Loader source as QUrl
Otherwise it tries to load it relative to the current protocol, e.g. qrc:/usr/share/... instead.
Face config in systemmonitor plasmoid shows up again
I guess this is fall out from (url basic type documentation) but more correct either way:
Note: In Qt 5, URLs were automatically resolved based on the current context when assigning them to any url property. This made it impossible to work with relative URLs and it created inconsistent behavior when reading back a URL previously written to a property. Therefore, the behavior was changed in Qt 6: URLs are not automatically resolved on assignment anymore. The individual elements that use URLs have to resolve them themselves.