Add Grafana dashboard for Cluster OPS

[weeco]

Usecase

As cluster ops I'd like to use the provided metrics in a separate Grafana dashboard to get more information about a specific topic. Right now there's only one dashboard which was created to get information by specifying a consumer group name. Instead I'd like to choose a topic and in return the dashboard shows all information it has about the topic, e. g.:

• Which consumer groups do consume this topic at which rate
• Messages In
• Message count
• Cleanup Policy
• ACLs (nice to have)

Additionally I am interested in:

• Topics which haven't got any consumer group offsets (aka not consumed topics - exclude system topics here)
• Total rate of all consumers together (as JMX metrics only provide a "messages in" metric) (maybe the same dashboard grouped by topic?)
• Top Consumer Groups with the highest offset commit rate (so that we can detect consumers which commit too often, and therefore stress the brokers more than needed)

All the above listed features for a Dashboard can be created without adding any further metrics in Kafka Minion

[weeco]

Topics which haven't got any consumer group offsets (aka not consumed topics - exclude system topics here)

Probably it makes sense to implement a new metric for that, which exposes the number of unique consumer groups which have offsets for a topic, like that which indicates there are 8 consumer groups which have at least one non expired group offset (for at least one partition):

kafka_minion_topic_subscribed_consumer_groups_count{topic="customers"} 8