Add use_fitcommondata

Created by: Zaharid

This is to be used for things like closure tests. Unfortunately the commondata files in the fit are stored after cuts, which makes it very difficult to interact with the existing validphys code. As a workaround we disable use_cuts. Yet, at the moment things like the fit comparison report will not work because they rely on knowing how to match data with cuts. I am not sue I want to try to fix that or instead consider this a hack to be reverted ASAP.