Remove Apache ZooKeeper from the Apache Kafka build. Also remove commons IO, commons CLI, and netty, which were dependencies we took only because of ZooKeeper.
In order to keep the size of this PR manageable, I did not remove all classes which formerly interfaced with ZK. I just removed the ZK types. Fortunately, Kafka generally wrapped ZK data structures rather than using them directly.
Some classes were pretty entangled with ZK, so it was easier just to stub them out. For ZkNodeChangeNotificationListener.scala, PartitionStateMachine.scala, ReplicaStateMachine.scala, KafkaZkClient.scala, and ZookeeperClient.scala, I replaced all the functions with "throw new UnsupportedOperationException". Since the tests for these classes have been removed, as well as the ZK-based broker code, this should be OK as an incremental step.
Reviewers: Chia-Ping Tsai <chia7712@gmail.com>
This is no longer required since we dropped support for Java 8. Also update `NOTICE*` and
`spotbugs-exclude.xml` files.
Reviewers: Chia-Ping Tsai <chia7712@gmail.com>, David Arthur <mumrah@gmail.com>