QmlDesigner: Move initialization to delayedInitiliaze()

In extensionsInitialized not all views are registered.

Change-Id: I8b7da87af4fceb5aed63c15ad43b6b67b7ca97c0
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/plugins/qmldesigner/qmldesignerplugin.cpp

@@ -318,6 +318,9 @@ bool QmlDesignerPlugin::delayedInitialize()
             emitUsageStatistics("QDSlaunchedFromQtC");
     }
 
+    if (QmlProjectManager::QmlProject::isQtDesignStudio())
+        d->mainWidget.initialize();
+
     return true;
 }
 
@@ -329,9 +332,6 @@ void QmlDesignerPlugin::extensionsInitialized()
         integrateIntoQtCreator(&d->mainWidget);
     });
 
-    if (QmlProjectManager::QmlProject::isQtDesignStudio())
-        d->mainWidget.initialize();
-
     auto &actionManager = d->viewManager.designerActionManager();
     actionManager.createDefaultDesignerActions();
     actionManager.createDefaultAddResourceHandler();