Add uncertainties for active volume calculation

[fhagemann]

Alternative to #80 (which can be used once https://github.com/legend-exp/legend-detectors/pull/48 is merged and according dummy values are added to legend-testdata).

I am not sure if Measurements can deal with asymmetric errors, so right now I'm estimating the uncertainty as the maximum number quoted as uncertainty in the metadata (pos and neg).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 42.08%. Comparing base (a660e56) to head (769ce11).
Report is 6 commits behind head on main.

Additional details and impacted files

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##             main      #87   +/-   ##
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  Coverage   42.08%   42.08%           
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  Files          26       26           
  Lines        1972     1972           
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  Hits          830      830           
  Misses       1142     1142           

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[fhagemann]

This implementation will only work if the latest metadata is loaded
(with the FCCD values provided in https://github.com/legend-exp/legend-detectors/pull/48), so make sure to upgrade the detector metadata before using this

[fhagemann]

@theHenks