This PR changes the external module resolution to eagerly bundle
node_modules, and some specific Next.js internal modules, if on the
`WEBPACK_LAYERS.server` layer. While resolving corresponding packages,
we use the `react-server` export condition (fallbacks to default).
A follow-up PR will be adding a Next.js option to opt-out specific
packages from being bundled on the server layer.
## Bug
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have a helpful link attached, see `contributing.md`
## Feature
- [ ] Implements an existing feature request or RFC. Make sure the
feature request has been accepted for implementation before opening a
PR.
- [ ] Related issues linked using `fixes #number`
- [x] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have a helpful link attached, see `contributing.md`
## Documentation / Examples
- [ ] Make sure the linting passes by running `pnpm lint`
- [ ] The "examples guidelines" are followed from [our contributing
doc](https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md)