Improve existing checks and add the possibility to subtract background (no fit)

A new check range_check_bkg_subtracted, which performs background subtraction, is added. The background is assumed to be linearly distributed, and no fit is performed. A simple sidebands subtraction is currently implemented. A few simple tests are added for this new check.

In addition, existing checks have been improved:

1. It is now possible to blind regions also when 2D histograms are saved (range_check_nd).
2. The unused parameter abs_tolerance has been removed.
3. Four optional parameters are added in range_check: exp_mean, exp_std, mean_tolerance and std_tolerance. If they are provided in input, it is checked if the observed mean and standard deviation values are compatible with the expected ones within the provided tolerances. If the check is passed, the fraction of events falling in the exp_mean +- exp_std region is saved in the CheckResult object.

Related to lhcb-dpa&1 (closed), https://gitlab.cern.ch/lhcb-dpa/project/-/issues/93

To do:

• update parsing.py
• update documentation (lhcb-datapkg/AnalysisProductions!149 (merged))

lbaplocal!26 (merged) has been opened to restore lb-ap check functionalities after the introduction of the changes applied in this MR

FYI: @djwhite @cburr