Include metadata details in DB sync messages

Acceptance Criteria

All dbsync messages to be appended a metadata JSON or wrapped into a JSON structure containing metadata about the sender and/or the message itself. Delete sync messages need to be updated  so that they are also sent in JSON format.

Each sender Spring Boot app to expose an db-sync.clientId application property that uniquely identifies an OpenMRS instance in a network of instances over which dbsync is used. (The exact case to be adapted to the usual keys syntax in the properties file.)
Specifically the node ID should be part of the metadata accompanying each message.