xAODMuonPrepData - Retrieve Readout element & add Identifier fields

This MR breaks out a couple of developments from !68350 (merged)

• Move macros shared amongst all prepdata classes into a seperate file to avoid code duplication
• Add setters & getters for the ReadoutElements. The links to the elements are not persistifiable. Hence, if the prepdata is loaded from disk, the object attempts to restore the link on-the-fly. The MuonDetectorManager is retrieved and then the associated readout element. If any of the two steps fails exceptions are thrown. The dynamic mechanism does not clobber with thread safety / avalanche scheduler problems because there'll be only one detector manager instance in Phase II.
• Adding additional information to the Measurements needed to construct the measurementHashes.
• Fix naming convention of the xAOD::AuxContainer classes

Tagging: @emoyse