Warn users when there's `head.js` being used in `app/`, and recommend to
use metadata. Will show a warning in console while rendering
Closes NEXT-268
---------
Co-authored-by: JJ Kasper <jj@jjsweb.site>
Co-authored-by: Lee Robinson <me@leerob.io>
This will reduce the bundle size and also give user proper hint to upgrade to `head.js`
* Mark `next/head` as noop in app dir
* Add warning for users to check the upgration guide to migrate it to head.js
Related to the build failure from #41931
We need to bundle `next/head` so that it can appear in the
flight-client-manifest, so we changed the behavior to not treat it as
non externals.
## Bug
- [x] Related issues linked using `fixes #number`
- [x] Integration tests added
- [ ] Errors have a helpful link attached, see
[`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md)
<!--
Thanks for opening a PR! Your contribution is much appreciated.
To make sure your PR is handled as smoothly as possible we request that
you follow the checklist sections below.
Choose the right checklist for the change that you're making:
-->
## 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`
- [ ] 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)
