Define "react-native-strict-api" type exports (#50909)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/50909

Enables and maps the `types_generated/` directory for `react-native` and `react-native/virtualized-lists` — exposing the new Strict TypeScript API entry points to React Native.

**New `"exports"` conditions**

- `"react-native-strict-api"` — The Strict TypeScript API opt in, exposing the `index.d.ts` entry point only.
- `"react-native-strict-api-UNSAFE-ALLOW-SUBPATHS"` — Opts into the new from-source generated types, but allows accessing subpaths (unsafe).
    - We intend for this unsafe condition to be an escape hatch for Frameworks only (i.e. Expo).

Note: In the case of `virtualized-lists`, we simply use the `"types"` condition — since this package did not expose any TypeScript API previously.

NOTE: Should we need to roll back JS Stable API phase 1, **this is the single diff to revert**.

Changelog:
[General][Added] - Configure the "react-native-strict-api" opt in for our next-gen TypeScript API

Reviewed By: cipolleschi

Differential Revision: D71969602

fbshipit-source-id: 291182cc826db8b33f21fc79698e6096876d17ef