compiler: Refactor connected_components

[EdCaunt]

Performance tweak to connected_components, using path halving (see https://doi.org/10.1145/62.2160). Yields appreciable speedup for big operators.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.26%. Comparing base (0164e85) to head (eb8f224).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3054   +/-   ##
=======================================
  Coverage   84.26%   84.26%           
=======================================
  Files         258      258           
  Lines       56982    56997   +15     
  Branches     4854     4855    +1     
=======================================
+ Hits        48016    48029   +13     
- Misses       8139     8144    +5     
+ Partials      827      824    -3     

Flag	Coverage Δ
pytest-gpu-aomp-amdgpuX	68.53% <100.00%> (-0.03%)	⬇️
pytest-gpu-gcc-	79.02% <100.00%> (-0.02%)	⬇️
pytest-gpu-icx-	78.95% <100.00%> (-0.03%)	⬇️
pytest-gpu-nvc-nvidiaX	69.11% <100.00%> (-0.02%)	⬇️

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