url: clean up WHATWG URL origin generation

- Use ordinary properties instead of symbols/getter redirection for
  internal object
- Use template string literals
- Remove unneeded custom inspection for internal objects
- Remove unneeded OpaqueOrigin class
- Remove unneeded type checks

PR-URL: https://github.com/nodejs/node/pull/12507


Reviewed-By: James M Snell <jasnell@gmail.com>