KIP-504 — Add new Java Authorizer Interface

Accepted Kafka 2.4 Security

Replaces the deprecated Scala kafka.security.auth.Authorizer trait with a new Java interface org.apache.kafka.server.authorizer.Authorizer, adding support for async authorization, broker start interceptors, and ACL metadata. The existing Scala trait cannot be depended on without pulling in kafka-core, creates compatibility barriers for third-party authorizer implementations (Ranger, Sentry), and lacks async support needed for remote authorization services.

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