[REVIEW ONLY] INTSAMPLES-132 AMQP Publisher Confirms/Returns

JIRA: https://jira.spring.io/browse/INTSAMPLES-132

Do not merge until Spring AMQP 1.3.5 is released.
We can live with this, although I'd prefer to have custom tasks for each `main` to avoid confuse.
See `helloworld` project configuration.