standardize_formula: handle ambiguous dash-hyphens

[rkingsbury]

Summary

There are various unicode characters that look like a dash or a hyphen, all of which can be used to represent "minus" in a chemical formula. This PR updates standardize_formula to handle the most common variants and converts them all to the most common "minus sign".

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.81%. Comparing base (92e93bd) to head (d9b0e65).
Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #264      +/-   ##
==========================================
+ Coverage   81.79%   81.81%   +0.02%     
==========================================
  Files           9        9              
  Lines        1494     1496       +2     
  Branches      257      258       +1     
==========================================
+ Hits         1222     1224       +2     
  Misses        226      226              
  Partials       46       46              

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