Fix: make parse comment more readable

[lwasser]

closes #91 to make the method easier to follow and more readable.
As it was there were multiple nested helpers making it super hard to follow / trouble shoot. i'm trying to surface each step and make each method name more user friendly with this draft pr.

[codecov]

Codecov Report

Attention: Patch coverage is 19.23077% with 21 lines in your changes are missing coverage. Please review.

Project coverage is 43.72%. Comparing base (484102a) to head (9fc98f7).

❗ Current head 9fc98f7 differs from pull request most recent head 7a106a2. Consider uploading reports for the commit 7a106a2 to get more accurate results

Files	Patch %	Lines
src/pyosmeta/parse_issues.py	19.23%	21 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #115      +/-   ##
==========================================
- Coverage   44.00%   43.72%   -0.29%     
==========================================
  Files           4        4              
  Lines         459      462       +3     
  Branches       73       73              
==========================================
  Hits          202      202              
- Misses        253      256       +3     
  Partials        4        4              

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[lwasser]

ok i have added some very basic tests and some structure around the test suite. i don't want to bloat this pr even further so i think this is ready for a review / merge. ✨