Implementation of notifications endpoints:
POST: Notification creation endpoint.
GET: Endpoint to get the current user's active notifications.
DELETE (without optional notifId): Endpoint to delete all of current user's active notifications
DELETE (with optional notifId): Endpoint to delete the current user's active notification with the Id notifId
Implementation of notifications endpoints: POST: Notification creation endpoint. GET: Endpoint to get the current user's active notifications. DELETE (without optional notifId): Endpoint to delete all of current user's active notifications DELETE (with optional notifId): Endpoint to delete the current user's active notification with the Id notifId