Support updating/rescheduling a pending notification

[auradigitaldev]

For my to-do list app, it would be nice to be able to update pending notifications. However, there is not enough data in the PendingNotificationRequest to be able to schedule an identical notification with maybe 1-2 different fields.

One example use case is updating the time zone of all of the pending notifications when switching time zones, but there are many others (updating a todo list item time, name, description, etc).