Kafka Streams helper operations

[jeqo]

Additional operations to include in KafkaStreamsTracing API to enable easier adoption of tracing as part of a Kafka Streams topology by emulating most-common operations (e.g. KStream#map, KStream#mapValues, KStream#foreach, KStream#peek) with Stream Transformers and Processors that have tracing enabled.

Changes:

KafkaStreamTracing operations added:

• ProcessorSupplier<K, V> foreach(String name, ForeachAction<K, V> action)
• TransformerSupplier<K, V, KeyValue<K, V>> peek(String name, ForeachAction<K, V> action)
• TransformerSupplier<K, V, KeyValue<K, V>> mark(String name)
• TransformerSupplier<K, V, KeyValue<KR, VR>> map(String name, KeyValueMapper<K, V, KeyValue<KR, VR>> mapper)
• ValueTransformerWithKeySupplier<K, V, VR> mapValues(String name, KeyValueMapper<K, V, VR> mapper)
• ValueTransformerSupplier<V, VR> mapValues(String name, ValueMapper<V, VR> mapper)

Ref #825

[codefromthecrypt]

looks good. had some documentation questions. Also, make sure the apis being wrapped are stable so we don't cause a rev-lock. Not sure if they are or not.

[jeqo]

loving suggestions function :)

[codefromthecrypt]

Thanks as always @jeqo and @ImFlog!