kafka: Implement ack handling

kafka: Implement ack handling

By default the kafka implementation we use doesn't require any kind of
acknowledgment, it just throws messages into the wind and lets them sit
where they may. Implement an option for KafkaHandler to specify the
number of acks (number of replicas that must record the message) and
some error handling to throw exceptions as necessary when there is a
problem.

Bug: T135159
Change-Id: I859dc791072db407f908b2f36be0d6704f1a6256