Prometheus support

[EladLeev]

Hi, I've made some changes to the metric reporter to be generic using abstract methods. In this PR I've added Prometheus support, but the idea is to let users extend it to whatever metric reporters they are using as long as they implement the BaseRes abstract method: https://github.com/EladLeev/kafka-utils/blob/prometheus_support/kafka_utils/kafka_rolling_restart/response.py

Using it in Production for few months now, but I didn't had a chance to finish it up with tests, proper documentation, and to resolve conflicts from main branch 🥲 -- if anyone want to assist, more than welcome!

Might resolve this one as well - https://github.com/Yelp/kafka-utils/issues/210

Thank you for the awesome project