streamline Event/EventPacker
- unify function names to allow the code that uses them be more generic
- prefer generic functions over cut-paste-modified code
- use emplace_back the way it is intended
- prefer fmt::format over std::stringstream
- prefer Gaudi::Property
- prefer switch over repeated if
- prefer std::abs over fabs
- convert {Un,}PackPrimaryVertices, {PVToRec,RecToPV}Converter to Gaudi::Functional
- prefer Gaudi::Property over declareProperty
- prefer range-based loops
- prefer fmt::format over std::ostringstream
- rename select_subrange into subrange
- prefer nullptr over 0
must be applied in conjunction with Moore!955 (merged)