run CMSSW from EL9

• compile the strict necessary (mostly Objects and Ntupliser)
  • CommonTools?
  • move Uncertainties/interface/Variation.h to Objects
  • move Objects/interface/Di.h to Darwin?
• CMSSW release for UL prod? (CMSSW_10_6_X)
• move handling of MetaInfo away from Ntupliser_cfg.py and Ntupliser.cc to mkNtuple (see example to upload a ROOT file that would contain the Metainfo)
• adapt mkNtuples to use singularity or docker (instructions from CAT & gitlab-profile!21 (closed))