KIP-1356 — Introduce IQv2 for headers-aware state stores

Accepted Kafka 4.4 Streams

Introduces IQv2 query types returning a new read-only ReadOnlyRecord interface exposing key, value, timestamp, and headers, and makes the pre-existing key, range, and window query types behave consistently against header-aware state stores regardless of how the store was built. KIP-1271 lets stores persist record headers but exposes no way to read them back: existing queries silently drop headers on adapter-built stores and fail with UNKNOWN_QUERY_TYPE on natively-built ones.

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