Summary:
- Add a typescript project to test `CodegenSchema.d.ts`. More tests for other .d.ts files will be added in future pull requests.
- The build script scans all snapshots from `react-native/codegen`'s typescript frontend and generates .ts files for each snapshot, but they are .gitignore-ed.
- `npm run build` will build these .ts files against `CodegenSchema.d.ts` after generating them.
- A failed jest case is included to ensure CI catch it, it will be removed before merged.
bypass-github-export-checks
## Changelog:
[General] [Added] - Add react-native/codegen-typescript-test to verify .d.ts files in react-native/codegen (1)
Pull Request resolved: https://github.com/facebook/react-native/pull/36562
Test Plan:
`npm run build` in `packages/react-native-codegen-typescript-test` and see all test files appear in `__generated__`.
## Screenshot

Reviewed By: rshest
Differential Revision: D44292277
Pulled By: cipolleschi
fbshipit-source-id: 8d79fe913f9563d64c92aae7c4f4e97a24ae9a21