New hgc clusters electrons

New clustering for HGC photons and electrons, including baseline calibration
@lgray - check carefully i didn't break much of your code
@vandreev11 - follow this PR as well
A photon gun sample produced with this is available in
/store/cmst3/group/hgcal/CMSSW/Single22_CMSSW_6_2_0_SLHC20_new_hgc_clusters_electrons-fullcalib/RECO