Graphics effect property should be moved from QDeclarativeItem to QGraphicsObject

Setter and getter functions are part of QGraphicsItem so the property should be part of QGraphicsObject, for the data binding to work signal graphicsEffectChanged needs to be declared in the same class as the property. QGraphicsWidgets need to define additional graphicsEffect property If the property isn't defined in the base class QGraphicsObject shared by declarative items and graphics widgets.