Bug 32573: Send ACK message to RabbitMQ before handling the job

Bug 32573: Send ACK message to RabbitMQ before handling the job

Splitting off this functionality from bug 32558. This is the comment that started this discussion: https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=32558#c15

From the O'Reilly book Mobile and Web Messaging:

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit b3c5bd02e15e5f2e5c0eae3b06f26083b4856f3d)
Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>
(cherry picked from commit 0f7b8008f7f1158f9b5aff9fa8c5b58cff28f000)

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>