`AnalysisEpic`: validate association between `MCParticles` and `GeneratedParticles`

[c-dilks]

Context:
https://github.com/eic/sidis-eic/blob/f7ca1f68352ed35ae830cdf85e2f42935f3a6840/src/AnalysisEpic.cxx#L148-L152

In particular, is using a double key in genidmap sufficient? It depends on how the corresponding collections were filled upstream.