dRICH: produce IRT geometry objects

We would like to connect the IRT geometry objects to the geometry description. We have tried doing this at the Juggler level, using GeoSvc, but find it more practical to keep the IRT geometry code integrated directly with the detector geometry code. We could automate the production of a "configuration" file containing IRT geometry objects, generated by src/DRICH_geo.cpp as needed.

This is how we ran for ATHENA, using athena!331 but we will need to think about how to best handle the extra configuration file in CI pipelines.