Allow custom binning in checks histograms
Checks histograms are currently hard-coded to have 50 bins in each dimension but it might be useful to allow users to customise the number of bins they want for each variable or perhaps scale it based on number of total entries.
Related to lhcb-dpa&1 (closed), https://gitlab.cern.ch/lhcb-dpa/project/-/issues/93