Resolve "Re-scale the dRICH"

Closes #10 (closed)

Notes:

• this is an initial re-scale of the dRICH geometry to be as close to the ECCE design as possible
• small changes to geometry and material properties from athena branch 144-irt-geometry have been implemented
• snout length is a few cm shorter than the ECCE design, to avoid overlap with a beamline component
• there are still some overlaps between the dRICH vessel and these other volumes (it may be too early to try to fix these):
  • world_volume/ECalBarrel_envelope
  • world_volume/FakeDIRC
  • world_volume/ForwardBackwardTrackerSubAssembly/ForwardGEM/ForwardGEM_layer1