Use MessagePack for serialization

[djsutho]

Currently we are using json for data serialization to/from kafka topics.

We should have the option of using MessagePack throughout the system as it has performance benefits and it makes it consistent with the ingest topic which defaults to using MessagePack.

[williewheeler]

We have a Kafka serde for MetricData, but we need serdes for the other data types too (e.g. MappedMetricData, Anomaly). MessagePack requires us to hand-craft these on a per-type basis.

[djsutho]

Actually might just be able to copy the json implementation and use this https://github.com/msgpack/msgpack-java/tree/develop/msgpack-jackson