Use the term origin to refer to scheme://host

[visnup]

Follow up to #490. Renames usages of "host" when referring to scheme://host to "origin."

I noticed the tests for this weren't really working with deepEqual on URL objects:

> require("assert").deepEqual(new URL("https://example.com"), new URL("http://foo.com"))
undefined
> require("assert").equal(String(new URL("https://example.com")), String(new URL("http://foo.com")))
Uncaught AssertionError [ERR_ASSERTION]: 'https://example.com/' == 'http://foo.com/'
    at REPL20:1:19
    at ContextifyScript.runInThisContext (node:vm:121:12)
    at REPLServer.defaultEval (node:repl:599:22)
    at bound (node:domain:432:15)
    at REPLServer.runBound [as eval] (node:domain:443:12)
    at REPLServer.onLine (node:repl:929:10)
    at REPLServer.emit (node:events:526:35)
    at REPLServer.emit (node:domain:488:12)
    at [_onLine] [as _onLine] (node:internal/readline/interface:416:12)
    at [_line] [as _line] (node:internal/readline/interface:887:18) {
  generatedMessage: true,
  code: 'ERR_ASSERTION',
  actual: 'https://example.com/',
  expected: 'http://foo.com/',
  operator: '=='
}