KIP-358 — Migrate Streams API to Duration instead of long ms times

Accepted Kafka 2.1 Streams

Replaces all `long`-typed millisecond duration parameters in the Kafka Streams public API (`Stores.windowedBy`, `KStream.groupByKey().windowedBy`, `KafkaStreams.close`, etc.) with `java.time.Duration`. Using raw `long` milliseconds provides no compile-time unit safety and makes API semantics ambiguous — callers cannot tell whether a parameter is seconds, milliseconds, or nanoseconds.

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