Additional attributes in Storage record delete notification events

Part 1 of Implementation of ADR - osdu/platform/system/home#93 Two java files have been created in this implementation.

1. Enum - DeletionType -> hard or soft
2. Model class - PubSubDeleteInfo -> which extends with extra attribute Deletion type to be used to publish deletion event

After this common lib code is merged another PR will follow in storage service using this model class to publish extra details