Sticky partitioner/

[RO-29]

Describe the solution you'd like
Hello, I don't see sticky partitioner option in this library, is it planned to support it?
It's supported in kafka 2.4+

Supporting documentation
https://www.confluent.io/blog/apache-kafka-producer-improvements-sticky-partitioner/

It seems available in shopify/sarama library (https://github.com/Shopify/sarama/search?q=sticky)

[Pryz]

kafka-go doesn't support sticky partition yet but any PR to add this feature is welcome :)