- Add `weak` to mock variables called `delegate`
- Delete `UserNotificationCenterSpy` and use `UserNotificationCenterMock`
- Remove Task.sleep in favour of mock closures along with expectations/fulfillment.
* NotificationManager tests
* More unit tests
* More tests, moved classes to separate files
* Removed warnings
* UserNotificationCenterProtocol as AnyObject
* Reverted back Package.resolved