fixup! feat: improve screen rendering framework

Author: acolombier

res/controllers/DummyDeviceDefaultScreen.qml

@@ -13,7 +13,7 @@ import Mixxx.Controls 1.0 as MixxxControls
 
 import "." as Skin
 
-Mixxx.Controller {
+Mixxx.ControllerScreen {
     id: root
 
     required property string screenId

src/qml/qmlmixxxcontroller.h

@@ -9,7 +9,7 @@ namespace qml {
 
 class QmlMixxxControllerScreen : public QQuickItem {
     Q_OBJECT
-    QML_NAMED_ELEMENT(Controller)
+    QML_NAMED_ELEMENT(ControllerScreen)
     Q_PROPERTY(QJSValue init READ getInit WRITE setInit
                     NOTIFY initChanged REQUIRED);
     Q_PROPERTY(QJSValue shutdown READ getShutdown WRITE setShutdown