KIP-1094 — Add a new constructor with nextOffsets to ConsumerRecords

Accepted Kafka 4.0 Consumer

Adds a `nextOffsets` map to `ConsumerRecords` that exposes, per partition, the offset to be fetched in the next `poll()` call (i.e., `lastOffset + 1`), pre-wrapped in `OffsetAndMetadata`. This allows Kafka Streams and other frameworks to commit precise next-fetch offsets without re-computing them from the last received record.

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