Add EvtBcVPPHad model and updated EvtPhiDalitz to use helicity amplitudes.

Summary:
Add EvtBcVPPHad model for Bc to Jpsi p pbar pi decays and generalise the particle ordering for EvtBcVHad decay files, courtesy of Aleksei Luchinsky, Dmitrii Pereima & Vanya Belyaev (LHCb).

Updated EvtPhiDalitz model to use helicity amplitudes and fixed the indices used in the EvtVector3R::dot() function, courtesy of Arnau Brossa Gonzalo & Antonio Romero Vidal (LHCb).

Closes T230

Test Plan: Added JSON test files for EvtBcVPPHad model, and updated the EvtPhiDalitz one.

Reviewers: abudinen, kreps, tlatham

Reviewed By: abudinen

Tags: #evtgen

Maniphest Tasks: T230

Differential Revision: https://phab.hepforge.org/D100