MaintenanceGui should also show productkeycheck pages

Change-Id: Ie1d7183e6420a17f34d7d199e80c34ab8e3d6db2
Reviewed-by: Iikka Eklund <iikka.eklund@digia.com>
Reviewed-by: Niels Weber <niels.weber@digia.com>
Reviewed-by: Kai Koehne <kai.koehne@digia.com>