refactor: git-proxy-cli package to TS + ESM (v2)

[jescalada]

Fixes #1064. Replaces #1065 due to merge conflicts.

I modified some things such as the CLI execution script because the original one (npx -- @finos/git-proxy-cli), oddly, no longer works.

I'd love to know better ways to handle the build/testing step and if the CLI flow works as it used to!

[netlify]

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🔨 Latest commit	276c98e
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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.76%. Comparing base (2950617) to head (276c98e).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1180   +/-   ##
=======================================
  Coverage   82.76%   82.76%           
=======================================
  Files          66       66           
  Lines        2780     2780           
  Branches      332      332           
=======================================
  Hits         2301     2301           
  Misses        431      431           
  Partials       48       48           

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