Implement conversion from LaTeX to our Markup XML

[mbollmann]

This reimplements functionality from bin/latex_to_unicode.py within the new library, needed for #4766.

Work in progress. Works in principle, but needs much more test cases to ensure feature parity with the previous implementation. Also, some normalization steps (as done in the old latex_to_unicode() function) are not yet ported.

[codecov]

Codecov Report

Attention: Patch coverage is 93.25843% with 6 lines in your changes missing coverage. Please review.

Project coverage is 92.64%. Comparing base (505a099) to head (28e6a0b).

Files with missing lines	Patch %	Lines
python/acl_anthology/utils/latex.py	92.10%	6 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff               @@
##           python-dev    #4787      +/-   ##
==============================================
+ Coverage       92.62%   92.64%   +0.01%     
==============================================
  Files              35       35              
  Lines            2645     2733      +88     
==============================================
+ Hits             2450     2532      +82     
- Misses            195      201       +6     

Files with missing lines	Coverage Δ
python/acl_anthology/text/markuptext.py	95.19% <100.00%> (+0.19%)	⬆️
python/acl_anthology/utils/__init__.py	100.00% <100.00%> (ø)
python/acl_anthology/utils/xml.py	98.57% <100.00%> (+0.18%)	⬆️
python/acl_anthology/utils/latex.py	96.12% <92.10%> (-3.88%)	⬇️

🚀 New features to boost your workflow:

• ❄ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.