QmlJS: Delay loading of default QML type descriptions

We definitely do not need to do this during startup of Qt Creator, delay
to first use.

Change-Id: I5942b5346aedc3d6b677918ad28a6c2924d09493
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

src/plugins/qmljstools/qmljsmodelmanager.cpp

@@ -261,7 +261,7 @@ QHash<QString,Dialect> ModelManager::languageForSuffix() const
 ModelManager::ModelManager()
 {
     qRegisterMetaType<QmlJSTools::SemanticInfo>("QmlJSTools::SemanticInfo");
-    loadDefaultQmlTypeDescriptions();
+    CppQmlTypesLoader::defaultObjectsInitializer = [this] { loadDefaultQmlTypeDescriptions(); };
 }
 
 ModelManager::~ModelManager() = default;