Associated Jpsi etac production (data and MC) (v2)

Reproducing ntuples for the analysis of associated Jpsi-etac prompt production, with Jpsi -> mu+ mu- and etac -> p+ p-. Also, reproducing ntuples for MC for two samples, Jpsi -> mu+ mu- as well as etac -> p+ p-. New DTFs have been added, and the Jpsi mass is no longer constrained by default. TISTOS variables specific to Jpsi and etac for the RD have been added. Some selection has been loosened.

(supersedes !2064 (merged)) The superseded ntuples can be deleted immediately.