QmlDesigner: Allow qml2puppet to mockup C++ types

This allows Qt Quick Designer to register a component that can serve
as a mockup for known C++ components registered in e.g. main.cpp.

In many cases those components are the interface to the C++ backend.
While the C++ components itself are not relevant for the gui designer,
the user has to be able to instantiate gui components that use such C++
components.

We use the CreateSceneCommand to forward a list of C++ types to
qml2puppet.
Those types are then registered so that the imports and object institation
works.

Change-Id: I1543912f233f9a783998f3c6a1b48981b342ee80
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

share/qtcreator/qml/qmlpuppet/qml2puppet/instances/qt5nodeinstanceserver.cpp

@@ -85,6 +85,8 @@ void Qt5NodeInstanceServer::resetAllItems()
 
 void Qt5NodeInstanceServer::setupScene(const CreateSceneCommand &command)
 {
+
+    setupMockupTypes(command.mockupTypes());
     setupFileUrl(command.fileUrl());
     setupImports(command.imports());
     setupDummyData(command.fileUrl());