Closes #15621: User notifications

[jeremystretch]

Closes: #15621

• Implement dynamic registration for event types
• Add event types for job failures and errors
• Alter event handling logic to enqueue events by canonical type rather than by the corresponding ObjectChange action type
• Introduce three new models: Subscription, NotificationGroup, and Notification
• Add post_save signal receiver to automatically generate notification for subscribed users
• Extend EvenRule to support sending notifications
• Add notifications dropdown in top navigation bar
• Provide user views for subscriptions & notifications
• Add model documentation

[arthanson]

Getting the following when checkout the code:

django.core.management.base.SystemCheckError: SystemCheckError: System check identified some issues:

ERRORS:
extras.Notification.event_type: (fields.E004) 'choices' must be an iterable (e.g., a list or tuple).

[arthanson]

See previous comment on getting SystemCheckError wasn't able to actually run it to test.

Also, should add model docs for the new models?

[arthanson]

Several crashes

[arthanson]

There is no confirmation of delete on a notification. Not very critical if you delete it and you don't want, but everything else in NetBox has a confirmation on delete so not sure if this was by design.

[jeremystretch]

There is no confirmation of delete on a notification.

Yeah, I modeled it after GitHub notifications: Clicking through to an object will mark the notification as "read," but not delete it. Deletion is a manual task, but does not require confirmation, so that notifications can be easily dismissed.

(I'm open to feedback about this during the beta, but suspect this approach will satisfy most users.)

[arthanson]

There is just one minor UI in the notification list there is an info icon that I think isn't supposed to be there (see screenshot) otherwise looks good:

[jeremystretch]

I added the icon to help convey each notification's urgency. We're currently using only info, but success, warning, and error are available as well.