feat: Poisson confidence intervals for data uncertainty in data/MC plots

[ekourlit]

Adding frequentist confidence interval error bars on poisson distributed data. These changes only affect the way of plotting the data error bars on figures.

[alexander-held]

Thanks for adding this! As discussed offline, I'll fix the tests to get this merged.

For reference: these are "Garwood" intervals used through hist.intervals.poisson_interval.

* use Poisson confidence intervals to draw uncertainty for data points in data/MC plots
* implementation uses "Garwood" intervals via hist.intervals.poisson_interval

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (860a834) to head (a555e83).

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #466   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           22        22           
  Lines         2082      2083    +1     
  Branches       340       340           
=========================================
+ Hits          2082      2083    +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.