Export processors as functions instead of values

[mdurling]

I noticed this in the k8s logs for both mds-event-processor and mds-telemetry-processor pods. Each container should only be referencing one processor. This was due to the stream processors being initialized on export. Changed processors to export a factory function that can be used to initialize them instead.

│ INFO "Creating KafkaStreamSink" "mds.event.annotated" {"clientId":"mds-event-processor"}                             │
│ INFO "Creating KafkaStreamSource" "mds.event" {"groupId":"mds-event-processor"}                                      │                                                                         │
│ INFO "Creating KafkaStreamSink" "mds.telemetry.annotated" {"clientId":"mds-telemetry-processor"}                     │
│ INFO "Creating KafkaStreamSource" "mds.telemetry" {"groupId":"mds-telemetry-processor"}