KIP-365 — Materialized, Serialized, Joined, Consumed and Produced with implicit Serde

Accepted Kafka 2.1 Streams

Adds Scala implicit conversions in the `kafka-streams-scala` module so that `Materialized`, `Consumed`, `Produced`, `Joined`, and `Serialized` objects automatically pick up the correct `Serde` from implicit scope without requiring explicit serde arguments. Without implicits, every DSL call in Scala requires verbose serde boilerplate identical to the Java API, negating the ergonomic benefit of the Scala wrapper.

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