fix(url): handle :port values in host setter

[watilde]

The current implementation incorrectly allows values like ":80" (empty host with port), resulting in foo://:80/to, while the spec requires failure if the host is missing. This update aligns behavior with the spec.

const NodeURL = require("url").URL;
const WhatwgURL = require("whatwg-url").URL;
const newHost = ':80';

const url = new NodeURL("foo://path/to");  
url.host = newHost;
console.log(url.href); // Wrong: foo://:80/to

const url2 = new WhatwgURL("foo://path/to");
url2.host = newHost;
console.log(url2.href); // Correct: foo://path/to

Refs: https://url.spec.whatwg.org/#host-state

If buffer is the empty string, host-missing validation error, return failure.

WPT tests for this case will be added in a follow-up PR.