lib: expose primordials object

Expose the internal `primordials` object to help with Node.js core
development.

```console
$ node --expose-internals -r internal/test/binding lib/fs.js
(node:5299) internal/test/binding: These APIs are for internal testing
only. Do not use them.
(Use `node --trace-warnings ...` to show where the warning was created)
```

PR-URL: https://github.com/nodejs/node/pull/36872


Reviewed-By: Bradley Farias <bradley.meck@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>