KIP-792 — Add "generation" field into consumer protocol

Accepted Kafka 3.4 Consumer

Ensures that the cooperative (incremental) rebalance protocol respects the `ownedPartitions` field advertised by members so the assignor can preserve existing assignments and minimize partition movement. Without correctly propagating owned-partition information the cooperative protocol can revoke and reassign partitions unnecessarily, negating its latency advantage over stop-the-world rebalance.

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