Add VeloHits, VeloTracks, UTHits and FThits to PrMultiplicityChecker

Adds the distributions of VeloHits, VeloTracks, UTHits and FThits to PrMCTools. New class PrMultiplicityChecker is created.

Following plots are important for the study of the reconstruction performance with high occupancy lead-lead collisions. These changes allow to plot the ghost rates and tracking efficiency afterwards, as well as to see the hardcoded limit for max number of hits/tracks in each subsystem.

followed by changes in Moore Moore!751 (merged)