Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/49724

Changelog: [internal]

This moves the type definitions for the globals defined by React Native from the repository root to the `react-native` package, in the same directory as the existing TypeScript definitions. This will make it easier for end users to configure the globals from RN using the right source of truth.

Reviewed By: huntie

Differential Revision: D70322032

fbshipit-source-id: 932df75ded0c254f2acb32e865cbbb9474c94159