DumpGeoConfig.py: don't crash if the `ForwardRegionGeoModelTool` has not been configured
The patch tested with the following commands:
python -m DumpGeo.DumpGeoConfig --detDescr ATLAS-R2-2016-01-02-01
python -m DumpGeo.DumpGeoConfig --detDescr ATLAS-R3S-2021-03-02-00
python -m DumpGeo.DumpGeoConfig --detDescr ATLAS-P2-RUN4-03-00-00
@rbianchi: are you OK with this?