Akram Yakubov

## Description Support extract-key kafka message transform. Fixes #1176

Not able to serve streampay demo UI **Steps to reproduce** 1. Build UI by following README in https://github.com/aklivity/zilla-demos/tree/main/extras-containers/streampay/ui 2. Use below config to server the UI ``` --- name: zilla-streampay-demo-ui...

Currently, it is printing ``` headers: :status: $.status zilla:correlation-id: $.correlationid ``` instead of ``` headers: :status: ${message.value.status} zilla:correlation-id: ${message.value.correlationId} ```

Currently, we only support by `$ref` ``` StreampayUsersMessage: contentType: application/avro payload: schemaFormat: application/vnd.apache.avro;version=1.9.0 $ref: '#/components/schemas/StreampayUser' ``` We should support ``` myMessage: payload: schemaFormat: 'application/vnd.apache.avro;version=1.9.0' schema: type: record name: User namespace:...

See [1208](https://github.com/aklivity/zilla/issues/1208)

Correlator stream should have reply begin before we initiate produce (or at least before we 'FIN' produce)