QML Observer: Refresh debug id's when new objects are created

Previously, the user had to navigate to the context of a qml item in
order to edit its source code in Live Preview mode. This change tells
the client to update when new objects are created on server-side, and
makes the editing possible without having to manually trigger updates.

src/plugins/qmljsinspector/qmljsdesigndebugclient.cpp

@@ -108,6 +108,8 @@ void QmlJSDesignDebugClient::messageReceived(const QByteArray &message)
         QStringList contextPath;
         ds >> contextPath;
         emit contextPathUpdated(contextPath);
+    } else if (type == "SCENE_ITEM_COUNT_CHANGED") {
+        emit treeRefreshRequested();
     }
 }