KAFKA-16143: New JMX metrics for AsyncKafkaConsumer

[FrankYang0529]

Add following metrics to AsyncKafkaConsumer:

• time-between-network-thread-poll-avg
• time-between-network-thread-poll-max
• application-event-queue-size
• application-event-queue-time-avg
• application-event-queue-time-max
• application-event-queue-processing-time-avg
• application-event-queue-processing-time-max
• unsent-requests-queue-size
• unsent-requests-queue-time-avg
• unsent-requests-queue-time-max
• background-event-queue-size
• background-event-queue-time-avg
• background-event-queue-time-max
• background-event-queue-processing-time-avg
• background-event-queue-processing-time-max

Committer Checklist (excluded from commit message)

• Verify design and implementation
• Verify test coverage and CI build status
• Verify documentation (including upgrade notes)