Bump Metro to ^0.83.1, lower minimum Node.js version to 20.19

Summary:
Metro release notes: https://github.com/facebook/metro/releases/tag/v0.83.1

The only public-facing change is a lowering of the minimum Node.js version from 22.14 to 20.19.

This will need picking to RN `0.81-stable`

Changelog: [General][Changed] Metro to ^0.83.1

Reviewed By: huntie

Differential Revision: D78895160

fbshipit-source-id: b9ccffe972249b73897f51c14873861e57a97161