librdkafka implementation

[alex-kozin]

Feature request

Description

I would like a librdkafka-based Watermill PubSub implementation (compatible with https://github.com/confluentinc/confluent-kafka-go)

Example use case

I have Confluent Kafka Go client and would like to use Watermill to abstract away the transport layer of my messages so it is easier for me to switch providers if/when needed. I want to use it the same way I would use an existing Kafka implementation based on IBM Sarama.

How it can look like in code

[m110]

Fun fact, that was the first implementation but we then switched because the dependency was difficult to work with: ThreeDotsLabs/watermill-kafka@e9cf629

If someone were to implement this, it might be best to keep it separate from the current watermill-kafka repository, not to mix the dependencies.