Next.js plugin for alternate bundler (#76186)
This adds a new package allowing users to opt-into using Rspack in place of webpack in Next.js. While there is some logic to handle rspack in core, the actual third-party dependencies are not included there, only conditionally loaded. This package:
- Includes the actual npm dependencies on `@rspack/core` and `@rspack/plugin-react-refresh`
- Sets the `NEXT_RSPACK` environment variable, which Next.js itself uses to load the dependencies
- It exists as a kind of no-op `withRspack` decorator. @timneutkens is this the best approach to this?
