Add overloads taking view interface instead of controller

People won't be using the controllers directly

examples/qtquick/customtitlebar/main.cpp

@@ -65,7 +65,7 @@ int main(int argc, char *argv[])
     auto dw3 = new KDDockWidgets::Views::DockWidget_qtquick("Dock #3");
     dw3->setGuestItem(QStringLiteral("qrc:/Guest3.qml"));
 
-    dw1->dockWidget()->addDockWidgetToContainingWindow(dw3->dockWidget(), KDDockWidgets::Location_OnRight);
+    dw1->addDockWidgetToContainingWindow(dw3, KDDockWidgets::Location_OnRight);
 
     // Access the main area we created in QML with DockingArea {}
     auto mainArea = KDDockWidgets::DockRegistry::self()->mainDockingAreas().constFirst();