Explicitly load CaloHitContribution whenever SimCalorimeterHit is used

See https://github.com/key4hep/k4FWCore/issues/82.

Whenever

sim_coll = [
    "MCParticles",
    "EcalEndcapNHits",
]

we need to modify to

sim_coll = [
    "MCParticles",
    "EcalEndcapNHits",
    "EcalEndcapNHitsContributions",
]