QmlDesigner: Take StageGroup into account in allDefinedStates

Since we add support StateGroups we also have to take them here.

Change-Id: I54a897e6edc4677e90ea64dd5c7334fc76a8f36f
Reviewed-by: Henning Gründl <henning.gruendl@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

src/plugins/qmldesigner/designercore/model/qmlobjectnode.cpp

@@ -569,6 +569,12 @@ QList<QmlModelState> QmlObjectNode::allDefinedStates() const
     for (const QmlVisualNode &node : qAsConst(allVisualNodes))
         returnList.append(node.states().allStates());
 
+    const auto allNodes = view()->allModelNodes();
+    for (const ModelNode &node : allNodes) {
+        if (node.simplifiedTypeName() == "StateGroup")
+            returnList.append(QmlModelStateGroup(node).allStates());
+    }
+
     return returnList;
 }