feat: add line resolution for rotated boxes

[charlesmindee]

This PR improves the line resolution heuristic: when we build a document with rotated boxes, lines are resolved the right way (with a rotation of the page).

Any feedback is welcome!

[fg-mindee]

Thanks! I added some comment, I think we need to ensure this is compatible with #488 and to fix the failing CI job 👍

[fg-mindee]

Small question in comment

[codecov]

Codecov Report

Merging #677 (8f524ce) into main (8382896) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #677   +/-   ##
=======================================
  Coverage   96.28%   96.28%           
=======================================
  Files         117      117           
  Lines        4523     4525    +2     
=======================================
+ Hits         4355     4357    +2     
  Misses        168      168           

Flag	Coverage Δ
unittests	96.28% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
doctr/models/builder.py	96.49% <100.00%> (+0.06%)	⬆️

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[fg-mindee]

Thanks for the clarification!