refactor: Add TypeScript support

[fabiovincenzi]

Overview
This PR introduces TypeScript to git-proxy and refactors relevant code to support it.

Changelog

• Added TypeScript configuration (tsconfig.json) with essential settings for strict type checking, ES6 compatibility, and JSX support.
• Added typescript and ts-node to manage TypeScript code compilation and execution.
• Updated the package.json to include TypeScript dependencies.
• Converted the main entry file from JavaScript (index.js) to TypeScript (index.ts).
• Modified the start script to use ts-node for running TypeScript files.

Thanks to @jescalada for the work on fixing CI issues on G-Research#31, which helped guide the necessary changes in this PR.

Related issue: #927

---

Note: Restored from deleted fork

This PR recreates the original PR #929, which was automatically closed due to accidental fork deletion.

** For discussions and reviews:** See the original PR #929

All commits are identical to the original with preserved git history.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.62%. Comparing base (43c6497) to head (f04e628).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1142   +/-   ##
=======================================
  Coverage   79.62%   79.62%           
=======================================
  Files          59       59           
  Lines        2479     2479           
  Branches      289      289           
=======================================
  Hits         1974     1974           
  Misses        461      461           
  Partials       44       44           

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[jescalada]

Reapproving this - it's a lot easier to see the changes now that merge conflicts have been resolved 👍🏼

@coopernetes @06kellyjac I suppose this could go into the first release candidate for v2? Or should we deal with the few remaining TS PRs and get it all in a single release? #960 #1063 #1065

[06kellyjac]

Yes, moving to providing js and types from dist should be done in v2.
https://github.com/yeoman/generator/blob/main/package.json#L23-L37

Also there's several useful things within git-proxy which we expect people to directly import from files e.g. config, which would break & should be exported properly.

[06kellyjac]

Suggested change

	plugins/
	plugins/

Missing EOL

[06kellyjac]

These files don't live in dist due to ./scripts/build-for-publish.sh

[06kellyjac]

considering the majority of commits are just update merges and there's 2 commits with the same message a rebase & cleanup would be ideal