Dead Letter Queue

1. In your internal/pubsub package, update your DeclareAndBind function. It should pass in an amqp.Table to the QueueDeclare function that includes a x-dead-letter-exchange key. The value should be the name of your dead letter exchange. This will tell RabbitMQ to send failed messages to the dead letter exchange.
2. Stop your clients and restart them. This should delete their auto-delete queues and recreate them with the new dead letter exchange configuration.

3. Run the same test as before by creating 2 clients: washington and napoleon.
   1. Have washington spawn a couple of units: spawn americas artillery
   2. Have napoleon spawn a unit: spawn europe cavalry
   3. Have washington move a unit into napoleon's territory: move europe 1

Napoleon's client should "Ack" the message, and Washington's client should "NackDiscard" the message. This time, check the queue in the RabbitMQ management UI. You should see the failed message in the dead letter queue.

You can check the "Get messages" section of the queue's page. Get the latest message with "Nack Requeue" so you can see the raw message data.

Run and submit the CLI tests with the message still in the dead letter queue (because to inspect it, you requeued it).