docs: Creating a UDP socket in the browser is possible

[guest271314]

Describe the bug

Re https://www.iroh.computer/docs/wasm-browser-support

This is because we can't port our hole-punching logic in iroh to browsers: They don't support sending UDP packets to IP addresses from inside the browser sandbox.
That is not technically true and correct.

WICG Direct Sockets is implemented in Chromium-based browsers in an Isolated Web App. A UDP can be created in the browser with UDPSocket interface https://wicg.github.io/direct-sockets/#udpsocket-interface.

E.g.,

var s = new UDPSocket({remotePort:7, remoteAddress:"185.215.195.137"});
s.closed.then(console.log).catch(console.error);
var {readable, writable} = await s.opened;
readable.pipeTo(
  new WritableStream({
    write({data}) {
      console.log(decoder.decode(data));
    },
    close() {
      console.log("close");
    }
  })
).catch(console.log);
var encoder = new TextEncoder();
var decoder = new TextDecoder();
var writer = writable.getWriter();

var message = (m) => {
  return {data: encoder.encode(m) }
};

await writer.ready;
await writer.write(message(`UDP socket in the browser on ${location.protocol} in ${navigator.userAgent}`));

Relevant Logs

Expected behavior
Update documentation to reflect what is technically possible in the browser re UDP sockets.

Platform(s)
Desktop:

• OS: Linux (Debian)
• Browser: Version 139.0.7227.0 (Developer Build) (64-bit)

Smartphone:

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Version [e.g. 22]

Additional Context / Screenshots / GIFs

[guest271314]

Creating TCP and UDP sockets from arbitrary Web pages https://github.com/guest271314/sockets.