added 2FJJMET analyser and stuff

[Polly-Li]

added 2fjmet analyzer and modified run_analysis to run 2fjmet
also added a couple of configs for managing the variables and cutflow

[kmohrman]

Thanks for this PR and I'm sorry for being very slow to take a look at it. I see there are very many scripts added and it's a bit hard to understand the bigger picture at first glance (and I'm not sure right now how much of the functionality in some of these scripts overlaps with existing functionality, and how much is orthogonal).

So, I think it would be helpful if you could add a bit more text to the PR description, to list the main scripts that are added and what their main function is. I think this would help me to understand the PR a bit better. Thanks!

[Polly-Li]

the main change is to add the analysis_processor_2FJMET_fromNano into run_analysis step (to produce a hist.pkl), and make_plots (to produce plots etc. from the hist.pkl)
the other scripts are helpers and tools for running these two steps.

for both step:
config/config_handling.py ->reading the following yaml file
config/cutflows/*.yaml -> define selections in each set of cutflow

for analysis processor:
config/variables -> where the kinematic variables to be plotted in hist are stored
MET2FJ_input -> input file to run_analysis

for make_plot
config/produce_sample_name_csv.py produces sample_name.csv, which is needed for make_plot (producing sample_dict for sorting MC sample by types e.g. bkg={QCD,EKW,etc.})
utils/tools -> saving metrics (e.g. s/sqrt(b)) when drawing plot