Refactor KafkaIO to use DeserializerProviders

BEAM-7310 introduced support for Confluent Schema Registry, even if the API did not explicitly mention DeserializerProviders it opened the option to use multiple providers of Deserializers. The goal of this ticket is to refactor the KafkaIO API to reflect this new concept both for local Deserializer resolution and Confluent Schema Registry based (notice that this one becomes better isolated).