Adding multiple phase spaces, and auxiliary observables

Also including the 5j3b phase space, and auxiliary observable in unfolding. This will not be compatible with old version of the unfolding code, and will have to be processed using newer version, starting from this Merge Request: https://gitlab.cern.ch/kcormier/uzh-ttbb-unfolding/-/merge_requests/7.

The additional phase space is implemented by simply adding extra information on to the end of the observable name, a more sophisticated way of doing this might be useful later on.

Auxiliary observables are implemented as a 2D histogram, currently the number of additional b-tagged jets (additional being those with the lowest b-tag score) passing the tight working point. The code is flexible to update this to other observables, or using different ones depending on the primary observable. Migration matrices are implemented as 3D histograms.

Binning has been updated based partly on the statistical studies done by Umberto, but not following them exactly.