KIP-1092 — Extend Consumer#close with an option to leave the group or not

Accepted Kafka 4.1 ConsumerStreams

Adds a `leaveGroup` boolean option to `KafkaConsumer#close()` (and `KafkaStreams#close(CloseOptions)`) so callers can control whether the consumer sends a `LeaveGroup` request before closing, triggering an immediate rebalance. Kafka Streams hardcodes `internal.leave.group.on.close=false` for efficiency during topology restarts, but this makes graceful scale-down scenarios wait for the session timeout to expire before triggering a rebalance.

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