Provide a parameter to make figure generation optional

[fhamood]

Is your feature request related to a problem? Please describe.
Generating plots after running Percolator in a rescoring run is a massive time sink and for some pipelines where Oktoberfest is used, generating the plots makes no sense in the first place.

Describe the solution you would like
Please add a parameter that makes plotting optional, which is accessible from the config file.