Harmonize Derive and DerivePullback

[vgvassilev]

#721

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.85%. Comparing base (3e11004) to head (6025a81).
Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1187   +/-   ##
=======================================
  Coverage   94.85%   94.85%           
=======================================
  Files          51       51           
  Lines        8972     8972           
=======================================
  Hits         8510     8510           
  Misses        462      462           

Files with missing lines	Coverage Δ
lib/Differentiator/ReverseModeVisitor.cpp	95.59% <100.00%> (ø)

Files with missing lines	Coverage Δ
lib/Differentiator/ReverseModeVisitor.cpp	95.59% <100.00%> (ø)