Record Contribution: Introduce Kafka client to accept Instance events related to Initial contribution from mod-inventory-storage

Purpose/Overview:

For initial record contribution mod-inventory-storage will publish domain events for every Instance record it currently stores. mod-inn-reach should have a Kafka listener (client) which will consume those events and call business logic to upload Instance data to D2R. The exact content of events and other messaging details will be provided within MODINREACH-80. It should be possible to configure client's characteristics like topic, consumer group, concurrency etc. 

The following Kafka client implementation from mod-search can be used as an example: KafkaMessageListener.java

Acceptance Criteria:

• mod-inn-reach is able to consume events sent by mod-inventory-storage for Initial Contribution process via provided Kafka client
• events can be consumed in batches
• client can extract instance id from each event and pass it further for processing
• it should be possible to retry event processing in case of failure. retry mechanism should be configurable
• client configuration can be defined in application properties