Multiple serializers

[vigoo]

It proved to be very useful when using Akka to be able to define multiple serializers identified by name as part of the protocol (https://doc.akka.io/docs/akka/current/serialization.html#rolling-updates). We were able to use this to do rolling updates in live system from Kryo with Scala 2.12 to Kryo with Scala 2.13 and eventually an alternative serialization library.

It would be nice to have the same capability in shardcake, for example by providing a Serializer which holds a map of other serializers and defines some header format to identify which one to use.