DGN: Ability to skip reading geometries (non-spatial only)

Reading DGN files (IGDS) can be very time consuming. Sometimes it is only necessary to read the attributes without having the geometries in FME. The idea is to introduce a parameter in the reader to not return FME geometries (return FMENull geometry) to speed up reading. This would be similar to the "Read Geometries as: Non-Spatial" option in the Revit reader.