Changes how font loaders are configured in next config, makes more sense since options can be optional. Also adds error for when font loaders are used from within node_modules.
## 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)
Moves font related types to `next/font` so they can be reused in font
loaders.
Adds an argument to font loaders, the relative path from the app root to
the module consuming the loader. Needed for resolving local files
relative to the module calling it. Also used to improve error message.
Adds `@next/font/local` font loader. Similar to `@next/font/google` but
used to host locally downloaded font files.
