[PoC] Adding Kafka as Event Publishing Alternative to Rabbit

[Herlitzd]

Related #465

Added an integration with Kafka using the Confluent.Kafka package.

I heavily followed the patterns established from the RabbitMq integration. At the moment, my testing has been limited to the integration testing that is included with this PR.

I would love to get some feedback, and discuss any changes that would need to be made in order for this integration to move forward.

Notes

• Due to the complexity of the Kafka configuration, I am leaking the Producer Configuration object out through the IEventFlowOptions builder:

  .PublishToKafka(new ProducerConfig { })
  

• In order to allow consumers to customize their partitioning scheme I am allowing the Kafka publisher to be configured with an optional Func<IDomainEvent, TopicPartition> topicPartitionFactory

Edit: Looks like the integration test is timing out, unfortunately a Kafka broker doesn't expose any kind of meaningful health check, at least not without adding a third container for diagnostics. I can try to crank up the timeout in the integration test, but I would rather not burn through your CI time if there are more structural concerns with this change to address first.

[ahernandez-allegion]

I'll be following this and may have my team take a look. Thanks for taking a stab at it.