Switch Babel parsing from legacy Flow plugin to hermes-parser (#46696)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/46696

Following D62161923, we began to lose sync with modern Flow syntax when Metro's `transformer.hermesParser` option is disabled. This config option loads Babel for transformation (instead of `hermes-parser`), which requires a Babel plugin to parse (not strip) Flow syntax.

This diff migrates us away from `babel/plugin-syntax-flow` (see also https://github.com/babel/babel/issues/16264) and uses the modern [`babel-plugin-syntax-hermes-parser`](https://www.npmjs.com/package/babel-plugin-syntax-hermes-parser) instead (a component of the modern Hermes Parser stack).

Following this change, new projects that unset `transformer.hermesParser` will compile.

Resolves https://github.com/facebook/react-native/issues/46601.

Changelog:
[General][Fixed] - Fix parsing of modern Flow syntax when `transformer.hermesParser = false` is configured in Metro config

Reviewed By: cipolleschi

Differential Revision: D63535216

fbshipit-source-id: d2c6ddec030d89e2698e03b76194cf3568d04e6b