Also, don't add a Global Settings component at import if the xml doesn't have any global settings (option/size/custom).
PiperOrigin-RevId: 495950899
Change-Id: I6599e8ea3f3a82729fc5c974fd7ced8eb93b277e
This also fixes a sensor data reading bug: previously, _sensorIndex was multiplied by 3 by MjEngineTool.
PiperOrigin-RevId: 451699887
Change-Id: I864bcbf8159857764854b25311a26ec5672125d9