Support for Kafka Queues (Share consumer)

[ozangunalp]

Provides a new Kafka Source to support Kafka Queues (Share Consumer client).

Kafka companion: shareConsume* methods

Kafka Connector:

• share-group flag to create Kafka Share Consumer client.
• ReactiveKafkaShareConsumer with polling stream without pause/resume. -> Keeps polling the consumer and retries on IllegalStateException thrown by the consumer.
• ReactiveKafkaAdminClient methods for share Consumer description
• Fixed commit and failure strategies to handle per-message acknowledgement. -> Tracks received messages and listens to committed acks. Applies a timeout for pending records that are never acknowledged. Sends RENEW acknowledgements for messages still in-processing
• Graceful shutdown waits for pending messages, trying to commit at each iteration.
• Topic-based Health check to check partition assignments to the current client.
• ShareGroupAcknowledgment metadata enables processing code to decide between different per-message ack type. Same nack metadata.
• Batch consuming mode with per-message acking.
• Deserialization failure handler flags to choose which ack type to apply on deserialization failure.

[ozangunalp]

CI green, but some share group tests may still be flaky. Re-running in case.