Q_PROPERTY REQUIRED has no effect on components loaded directly from C++ API

The REQUIRED keyword in Q_PROPERTY simply does nothing for things loaded by QQmlComponent::loadUrl + beginCreate + completeCreate.

For the context (no pun intended), I discovered it because in KDE/Plasma some QQuickWindow subclass initializes views from components whose initial properties are set directly on the object one by one, bypassing the modern QQmlComponent::setInitialProperties infrastructure — which is why our kqml tool loads files that qml6 refuses to.