- added status flag to PV class for monitoring

patch generated by https://gitlab.cern.ch/lhcb/LHCb/-/jobs/35429884

perform some renaming of locations and revert back changes to get closer to master and be better backward compatible

- moved 'populate' code to Rec
- further optimized packing by not storing fields that can be recomputed
- adapted the unbiased code to use 'velosegmentids' derived from LHCbIDs

removed old PrimaryVertex class and replaced by simple new one

- use this as a base class of ExtendedPrimaryVertex, the class stored by
  PrimaryVertexContainer
- introduce old--style packers/unpackers for PrimaryVertex
- added constexpr to propertyName of old-style packers
- added packing_mapping for soatype packers

- add pv unpacking to simple output check

- add routine to return single refitted unbiased vertex

PrimaryVertexContainer
- added unit test for PrimaryVertices

- streamlined PV unbiasing code
- updated Particle packing checker

add properties needed for packing  to PrimaryVertices
added PrimaryVertices to selective packer/unpacker

and make `unpack` return a StatusCode to know when an unpacker has
failed, in which case, if available, another unpacker for the same
CLID can be tried