crypto: add better scrypt option aliases

Make parameter names available in a human-readable way, for
more accessible/self-documenting usage of the `scrypt` functions.

This implements a review comment from the original PR that has
not been addressed.

Refs: https://github.com/nodejs/node/pull/20816#discussion_r189220776

PR-URL: https://github.com/nodejs/node/pull/21525


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>