Kafka streams: add possibility to choose multiple output topics

KIP draft: https://cwiki.apache.org/confluence/display/KAFKA/KIP-422%3A+%5BStreams%5D+Support+multiple+topic+resolution+in+TopicNameExtractor

There is an awesome feature which was added in 2.0 kafka stream - possibility to choose dynamically the output topic for topology, but in some cases it could be useful to chose several topics withing the same cluster.

Personally me - I met such case: I needed to route message based on its content and by routes configuration to several topics.

I've made a 'proposal' PR for this, unfortunately I couldn't find better way to implement this:

https://github.com/apache/kafka/pull/5801

If this approach is OK, and improvement could be done in future versions, please let me know and I'll finish PR code.