chore: add script to bump major version

[crenshaw-dev]

The PR for bumping major versions touches hundreds of files. To ease the review process, I want a script we can run and be confident that the only changes are the ones made by the script.

I've validated the script by running it locally, then running codegen, lint, and unit tests.

You can see an example of the generated PR here: crenshaw-dev#30

[bunnyshell]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 55.17%. Comparing base (5508d1f) to head (f848766).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #21363      +/-   ##
==========================================
- Coverage   55.20%   55.17%   -0.04%     
==========================================
  Files         337      337              
  Lines       57057    57057              
==========================================
- Hits        31501    31483      -18     
- Misses      22858    22871      +13     
- Partials     2698     2703       +5     

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[agaudreault]

LGTM