qtquick: Added a FrameworkWidgetFactory too

The impl is dummy, but at least Config doesn't return a nullptr
one, meaning we can have more involved tests for QtQuick

src/qtquick/Platform_qtquick.cpp

@@ -19,7 +19,7 @@
 #include "qtquick/Window_qtquick.h"
 #include "private/DockRegistry_p.h"
 #include "private/DragController_p.h"
-#include "FrameworkWidgetFactory.h"
+#include "FrameworkWidgetFactory_qtquick.h"
 
 #include <QQmlEngine>
 #include <QQuickStyle>
@@ -76,7 +76,7 @@ std::shared_ptr<Window> Platform_qtquick::windowFromQWindow(QWindow *qwindow) co
 
 FrameworkWidgetFactory *Platform_qtquick::createDefaultFrameworkWidgetFactory()
 {
-    return {};
+    return new DefaultWidgetFactory_qtquick();
 }
 
 Window::Ptr Platform_qtquick::windowAt(QPoint globalPos) const