WS-222: Ingestion-complete email notification

Changes

• Add new ingested_email notification template

  • Reads:

    Dear User,
    
    Thank you for using NRAO Workspaces.
    
    Your null request #42 has successfully had its products ingested into the archive.
    
    Best regards,
    NRAO Workspaces

• Configure notification service and capability service to send new notification upon reception of an ingestion-complete message

Completes WS-222 and subtasks