Add ZQM request-reply pattern
Currently we have three distribution mechanics on two distribution patterns:
- request, then reply
- pull/api
- broadcast
- ZMQ stream
- Blockchain transactions
I think we should add a ZMQ request-reply to the request, then reply pattern and re-structure accordingly. This allows implementations to simplify and the rest api can be built as a layer on top of the ZMQ request-reply pattern.