url: add a got host pattern in url.js

Add a hostPattern variable for readable purposes

PR-URL: https://github.com/nodejs/node/pull/9653


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Brian White <mscdex@mscdex.net>