Optimize graph calculus

[Sichao25]

• Combine graphize_velocity_coopt and _graphize_velocity_coopt into one function.
• Add the weighted mode for divergence.
• Add a few tests for graph calculus

[codecov-commenter]

Codecov Report

Merging #557 (88b8577) into master (153f5b7) will increase coverage by 0.40%.
The diff coverage is 49.36%.

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

@@            Coverage Diff             @@
##           master     #557      +/-   ##
==========================================
+ Coverage   22.32%   22.73%   +0.40%     
==========================================
  Files         158      160       +2     
  Lines       26356    26406      +50     
==========================================
+ Hits         5885     6003     +118     
+ Misses      20471    20403      -68     

Files	Coverage Δ
tests/test_estimation.py	100.00% <100.00%> (ø)
tests/test_tools.py	100.00% <100.00%> (ø)
dynamo/tools/graph_operators.py	24.63% <0.00%> (ø)
dynamo/tools/graph_calculus.py	19.29% <13.18%> (+9.50%)	⬆️

... and 2 files with indirect coverage changes

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more