Add type hints to parsers

[GlassOfWhiskey]

This commit enables type hints within Python generated parsers. by refactoring how the codegen logic handles instance types. Results are fully-typed Python objects ready to be compiled with mypyc.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.33%. Comparing base (80c817a) to head (a8947d0).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #993      +/-   ##
==========================================
+ Coverage   83.27%   83.33%   +0.06%     
==========================================
  Files          22       22              
  Lines        5023     5042      +19     
  Branches     1195     1198       +3     
==========================================
+ Hits         4183     4202      +19     
  Misses        558      558              
  Partials      282      282              

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