QmlDesigner: Expose component url

Change-Id: I2b1708e6f87b00ad0b56c04f591ba24720a886ba
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

share/qtcreator/qml/qmlpuppet/qml2puppet/instances/objectnodeinstance.cpp

@@ -768,6 +768,8 @@ QObject *ObjectNodeInstance::createComponent(const QString &componentPath, QQmlC
             qWarning() << error;
     }
 
+    object->setProperty("__designer_url__", QUrl::fromLocalFile(componentPath));
+
     return object;
 }