Add transaction support

[vervoorn]

Is your feature request related to a problem? Please describe.
In our application we consume and produce multiple (applying a function). To guarantee exactly processing, we would like kstreams to support kafka's transactional consume-produce pattern such as described here:
https://www.confluent.io/blog/transactions-apache-kafka/
aiokafka support: https://aiokafka.readthedocs.io/en/stable/examples/transaction_example.html

Describe the solution you'd like
a context manager to apply to the processing code (see aiokafka example)

Describe alternatives you've considered
direct use of aiokafka but this would mix libraries (and create direct dependency on aiokafka)