Ensure imports also have historical activity in bilateralization

[junukitashepard]

Ensure imports also have historical activity in bilateralization.

The current bilateralize tool leads to certain commodities not being balanced at the trade level (e.g., "shipped", "piped"). This is due to improper historical calibration of imports.

How to review

• Read the diff and note that the CI checks all pass.

PR checklist

• Continuous integration checks all ✅

[codecov]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.3%. Comparing base (1f7fe08) to head (d2137bf).

Files with missing lines	Patch %	Lines
...e_ix_models/tools/bilateralize/bare_to_scenario.py	0.0%	1 Missing ⚠️
...odels/tools/bilateralize/historical_calibration.py	0.0%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #480     +/-   ##
=======================================
- Coverage   73.3%   73.3%   -0.1%     
=======================================
  Files        301     301             
  Lines      24429   24430      +1     
=======================================
  Hits       17914   17914             
- Misses      6515    6516      +1     

Files with missing lines	Coverage Δ
...e_ix_models/tools/bilateralize/bare_to_scenario.py	68.0% <0.0%> (ø)
...odels/tools/bilateralize/historical_calibration.py	26.5% <0.0%> (-0.1%)	⬇️

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[junukitashepard]

The same tests used for bare_to_scenario and historical_calibration should cover these changes.