[Event Hubs] Add support for token cancellation in send requests

[ShivangiReja]

Allow users to cancel a send request as described in #2641 (comment) for send().

This PR uses addEventListener and removeEventListener of Aborter class.

Added onAborted listener using addEventListener method that listens aborted request and throws error when user calls aborter.abort(). It means that at any time if user wants to cancel the send request they can create an instance of Aborter and call abort().

example:

async function main(): Promise<void> {
  const client = EventHubClient.createFromConnectionString(connectionString, eventHubName);
  const partitionIds = await client.getPartitionIds();
  const aborter = Aborter.none;
  const sender = client.createSender({ partitionId: partitionIds[0] });
  const events: EventData[] = [];

  for (let index = 0; index <= 1000; index++) {
    events.push({ body: `Hello world...!!!${index}` });
  }
  console.log("Sending batch events...");
  try {
    sender.send(events, { cancellationToken: aborter });
    await delay(2000);
    aborter.abort();
  } finally {
    await client.close();
  }
}

[ramya-rao-a]

Since rest of the "error" scenarios in this file are using the "reject the promise" pattern, lets do the same here instead of throwing the error.

return reject(new Error(desc))

Also, the current messaging implies that we were not able to send the message, and so it is aborted. Instead the message should be that the send operation has been cancelled by the user

[ramya-rao-a]

I have updated this with 710ddd9

[ShivangiReja]

Reverted reject(new Error(desc)) -> throw new Error(err)

If we reject the promise, it continues the retry operation with this error:

And this error is retryable, so program continues the operation and doesn't exit.

If we throw the error, program works as expcted.

[ramya-rao-a]

When the send operation is successful, we should remove the listener that we added here, else we will soon hit the limit for the number of listeners an event can have. Can you check how the Aborter class allows us to do that?

[ramya-rao-a]

We might need to use addEventListener and removeEventListener methods instead of onAbort