Iterate over acknowledgements as they arrive

[darrachequesne]

Is your feature request related to a problem? Please describe.

When emitting with multiple acknowledgements, one has to wait for all responses (or the timeout).

const responses = await io.timeout(1000).emitWithAck("hello");

// then process all responses

Describe the solution you'd like

Iterate over the responses as they arrive, something like:

try {
  for await (const ack of io.timeout(1000).emitWithAckIterator("hello")) {
    // process one single response
  }
} catch (e) {
  // handle timeout
}

Describe alternatives you've considered

N/A

Additional context

Related: #5062