feat: Add support for deterministic listener ports (based on broker ID)

[justinrlee]

This is an enhancement to the dynamic listeners capability, which adds this functionality:

• Is enabled via the --deterministic-listeners flag
• When enabled (with dynamic listeners), use broker ID + minimum port to determine listening port (this means that if multiple instances are run in front of a Kafka cluster, all instances will use the same listening ports)
• Maintain a mapping of broker IDs to broker addresses (and net.Listener objects)
• If we see a broker with the same broker ID, but a different upstream listener, close the net.Listener and create a new one pointing at the new upstream listener

This is built to support clusters where broker hostnames and ports are not deterministic. Specifically, multiple Confluent Cloud cluster types re-use broker IDs with randomly generated hostnames; this PR enables the Kafka-Proxy to work with these Confluent Cloud clusters.

@everesio any thoughts on this? Would love your input here!