This PR promotes and renames experimental configuration options related
to server bundling:
- `serverComponentsExternalPackages` -> `serverExternalPackages`
- `bundlePagesExternals` -> `bundlePagesRouterDependencies`
Existing docs for `serverComponentsExternalPackages` was changed.
New docs for `bundlePagesRouterDependencies` were added.
Closes NEXT-3332
This avoids the need to manually check when these get out of sync by
having an automated check to keep them in sync when one or the other is
updated.
x-ref: https://github.com/vercel/next.js/pull/62966
Closes NEXT-2734
