url: move originFor, domainToAscii and domainToUnicode

Move non-standard methods to `url` module instead of exposing as
static methods on the `URL` object.

PR-URL: https://github.com/nodejs/node/pull/10512


Reviewed-By: Italo A. Casas <me@italoacasas.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>