- Add `MissingQueueEvent`
- Fix detection of a deleted queue in recovery - previously incorrectly used the
absense of the queue in `consumersByQueue`, which can be empty if missing during
start
- Add an index to `SimpleConsumer`
- When adjusting consumer counts, look for gaps in the index sequence because reducing
the consumer count can remove any idle consumer.
- Change consumers to restart to a `Set` to avoid OOM when no broker
(see https://github.com/spring-projects/spring-amqp/pull/642)
- Unconditionally add consumers to `consumersToRestart`
