* feat: added api to get notifications for users
* feat: added api to get count of notifications
* feat: added api to mark notifications as seen
* feat: added index on app_name in notification table
* refactor: updated api view parent and url
* refactor: resolved linter issue
* feat: added enrollment API for notification config
* feat: added apps.py in notifications
* feat: added waffle flag for notification app
* feat: added proper docs for the API
