url: make WHATWG URL properties spec compliant

* Set exposed attributes of the interface enumerable
  and configurable, as required by the spec.
  See: https://heycam.github.io/webidl/#es-attributes
* Make sure `URL#searchParams` returns `[[SameObject]]`
* Add the missing `URL#href` setter
* Reorder the properties to match
  https://url.spec.whatwg.org/#api
* Add tests for the ECMAScript property attributes

Fixes: #10376

Author: joyeecheung