Readouts and calo cell position

[BrieucF]

LAr calo cell positions used to be derived in several step, relying on CreateVolumePositions and two different readouts (see e.g. runCaloSim.py). This feature should be recovered and/or refactored.

[vvolkl]

Since edm4hep does not have two different types for Calo hits with / without position I don't think a separate algorithm like this makes sense. Looking at the workflow you linked, I think the positon should be set directly in CreateCaloCells. I'll try to refactor the code into a tool and add it there