Draft: xAODMuonPrepData: Add missing classes to selection.xml and fix typo

As discovered in !72886, there seem to be some issues with xAODMuonPrepData.

Will fix them in this MR.

@jojungge @goblirsc I'm a bit confused about the RPC and (s)TGC,Strip, Pad, Wires and how it all fits together. Do we really need all these concrete types? Could we not have more generic measurements to contain this information? Or is the plan to use Measurements here? Basically I’m not sure all the persistency is working, nor that the RDO convertors are outputting this correctly. But step one is writing down the intended design so we can make some unit tests.