URL: add host setter tests for empty host with port

[watilde]

This PR adds tests to capture the following difference in host setter behavior:

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); // => foo://:80/to

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

According to the WHATWG URL Standard, setting host = ":80" when the host is missing should fail, rather than produce an empty host with a port.

Refs: ada-url/ada#963