21.2: Add PFlow fJVT in HIGG1D2
Implementation of PFlow fJVT in derivations, following instructions from: https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/PileupJetRecommendations#Derivation_level_variables
Edited by Ioannis Nomidis
Implementation of PFlow fJVT in derivations, following instructions from: https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/PileupJetRecommendations#Derivation_level_variables