KIP-330 — Add retentionPeriod in SessionBytesStoreSupplier

Accepted Kafka 2.1 Streams

KIP-330 adds a `retentionPeriod()` method to `SessionBytesStoreSupplier`, parallel to the existing method on `WindowBytesStoreSupplier`. Without it, the `StoreBuilder` wrapper cannot determine the appropriate changelog topic retention period for session stores, causing the changelog to use an incorrect or default retention that may not cover the full session window.

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