QmlDesigner: Preview size is now changeable

You can now change the preview size with
rootModelNode.setAuxiliaryData("previewSize@Internal", size);
If size is null it will use the bounding box size.

Change-Id: Icbe747ccc5a2e26e79783825d2ed94ecc640012b
Reviewed-by: Michael Winkelmann <michael.winkelmann@qt.io>
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

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

@@ -1397,8 +1397,7 @@ void NodeInstanceServer::view3DAction(const View3DActionCommand &command)
     Q_UNUSED(command)
 }
 
-void NodeInstanceServer::changeLanguage(const ChangeLanguageCommand &command) {}
-}
-
-
+void NodeInstanceServer::changeLanguage(const ChangeLanguageCommand &) {}
 
+void NodeInstanceServer::changePreviewImageSize(const ChangePreviewImageSizeCommand &command) {}
+} // namespace QmlDesigner