CB-527: basicQos(prefetch) on the consume channel before basicConsume, configurable
via broker.prefetch (default 32), so an undrained inbox backlog stays on the broker
instead of growing the JVM heap without limit.
CB-528: publish moves to its own confirm-mode channel with mandatory=true and a
return listener, so an unroutable or unconfirmed reply now throws instead of
vanishing silently. The confirm callback checks the per-message returned flag
(set by the return listener, which the broker always fires before the matching
confirm) so an acked-but-returned publish is still reported as a failure. The ack
path stays on its own channel/lock and never waits on a publish confirm.
Dai Ha
4fa6553db5