[lvthanh03]

Ports the producer that sends commit log entries from confluent_kafka.Producer to arroyo's KafkaProducer.

This changes:

• Swaps to arroyo producer in MultistorageCollector and ProcessedMessageBatchWriter
• close() on each batch now waits on the produce futures, so a failed commit log write raises before the batch's offsets are committed
• ConsumerBuilder.flush() closes the producer at shutdown, which also sends anything still queued
• Adds a test for commit log production and for failed delivery

Refs STREAM-1930

[linear-code]

STREAM-1930