Move Phys/Particle2MCTruth to Rec?

I see that at least the algorithm MCMatchObjP2MCRelator in package Phys/Particle2MCTruth is needed upstream in the stack in Rec by Phys/MCAssociation/src/MCTruthAndBkgCatAlg.cpp. It hence seems Phys/Particle2MCTruth should be moved to Rec. And if the tool is only needed by one algorithm then the simplest may be to move the tools to Phys/MCAssociatio, avoiding a spurious extra package.

I'm assigning to you @amathad and @pkoppenb but that's more for the relevance to stuff used in connection with FunTuple for MC matching. What do you think?