Draft: Move Particle2MCTruth to Rec

The classes in this package are used in BTagging and MCTruthAndBkgCatAlg.cpp which are both in Rec. It doesn't make sense to have Particle2MCTruth in Analysis.

assigned to @pkoppenb

added DPA-WP3 cleanup lhcb-run3-cleanup labels

That would require also moving Analysis::LoKiPhysMCLib which I don't think is a good idea. So let's leave like that for the time being.

closed