KIP-1337 — Add Protobuf MessageFormatter for Kafka Console Consumer

Discussion ConsumerClient

Adds org.apache.kafka.tools.consumer.ProtobufMessageFormatter, a MessageFormatter implementation that loads .proto definitions from a user-specified directory at runtime and renders binary Protobuf values as human-readable JSON-like output via --formatter and --property proto.dir/message.type. Kafka ships no built-in way to inspect Protobuf payloads from the console consumer without schema registry access, so developers debugging locally must write ad hoc deserialization scripts.

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