Fix QMetaObject type handling in QQmlJSTypeResolver

We changed how const is handled in qmltypes/the compiler library (in https://codereview.qt-project.org/c/qt/qtdeclarative/+/441203); this breaks however how we set-up the metaObjectType in QQmlJSTypeResolver.

Simply dropping the const there might not be enough, as we still need to add it when generating (C++) code for locals of that type.