fix!: GeoPosition z value

• in the conversion for a GeoPosition the environment.GetConverter()->Convert() gets lat/lon as input and therefore only calculates x and y but z is neglected (0)
• According to OSC XML if in a GeoPosition the lat/lon position is on a lane, then the altitude/z-coordinate is specified to be at the road surface: https://publications.pages.asam.net/standards/ASAM_OpenSCENARIO/ASAM_OpenSCENARIO_XML/latest/generated/content/GeoPosition.html