Addd jet systematic tool and add the possibility to vary the jets before retagging

Added a tool to apply jet systematic variations before retagging starts. It allows us to evaluate the jet systematic uncertainties' impacts on the tagger. It is a function mainly added to perform the MC extrapolation studies.

Now, we can run:

ca-dump-retag -c ../training-dataset-dumper/configs/EMPFlowSys.json -m 100 /eos/user/b/biliu/mc20_13TeV/DAOD_FTAG1.31730559._003170.pool.root.1 -j JET_Flavor_Response -S -1.0

-j follows a list of systematic variations (but the anticipated workflow is to run with only one), -S determines whether we want up (1.0) or down (-1.0) variations.

The tool is added in a minimal way. For instance, no safety checks against wrong systematic inputs or wrong config combinations are present at the moment.

Tested in the latest nightly (Jan22) and an FTAG1 ttbar derivation with p5448.