Support for the web streams API

[JustinBeckwith]

Greetings folks, and thanks for the lovely library! I am trying to update an older codebase that was using this module, and running into issues with the WritableStream interface. The example here is great if you're using the node.js native stream module, but isn't compatible with web streams. This is making some of the piping I'm trying to from fetch to this module kind of difficult.

edit: Being more specific, I am looking for this method: https://nodejs.org/api/stream.html#streamwritabletowebstreamwritable

Supporting a web native stream API, or a pointer in a better direction for piping a stream from fetch directly to the parser would be lovely ❤️