Draft: (AFT-764) FTAG2 content update for GN3
- remove track thinning
- add electron CP contents
- add CHSG charged/netrual PFO
- add truth particle
- move AntiKt4EMPFlowJets to AllVaribles
- add jet skimming: at least 1 jet with pt > 15 GeV
Edited by Ligang Xia