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 #31, which helped guide the necessary changes in this PR.

Related issue: finos#927

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Additional details and impacted files

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##             main      #35   +/-   ##
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  Files           ?       48           
  Lines           ?     1680           
  Branches        ?        0           
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  Hits            ?      992           
  Misses          ?      688           
  Partials        ?        0           

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