Add readable and writable stream properties to Web Socket API

[AMorgaut]

Almost Everything is in the title ;-)

ReadableStream from the Stream API is already used in the Fetch API

Streams were also considered for the UDP TCP Socket API via readable and writable UDPSocket and TCPSocket properties.

Web Sockets is probably one of the APIs for which such stream API would be the most pertinent

[domenic]

This was previously discussed at https://www.w3.org/Bugs/Public/show_bug.cgi?id=23992; it's fairly complicated, and mostly redundant with fetch(), it turns out.

[annevk]

Yeah, in fact, using fetch() would give you slightly better performance and it's H2-compatible.

[annevk]

Once upload streams are a thing anyway, as per yutakahirano/fetch-with-streams#66.

[annevk]

It seems this would be addressed by #48, potentially.