Implement optimizer rule to eliminate double distinct

[ChrisJar]

Closes #925

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.59%. Comparing base (7da66be) to head (b464529).
⚠️ Report is 180 commits behind head on main.
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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1008      +/-   ##
==========================================
+ Coverage   80.47%   80.59%   +0.11%     
==========================================
  Files          75       75              
  Lines        4231     4231              
  Branches      765      765              
==========================================
+ Hits         3405     3410       +5     
+ Misses        662      653       -9     
- Partials      164      168       +4     

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