ref https://linear.app/tryghost/issue/ENG-1254
- when a subscription is canceled automatically by Stripe (e.g. due to
multiple failed payments), we now send a staff notification
- logic before: if a member cancels a sub in Portal, then send a staff
notification
- logic now: if a subscription was active, but is now set to cancel
immediately or at the end of the billing period, then send a staff
notification.
- with that logic change, we now send a cancellation staff notification
when:
1. A member cancels their sub in Portal (existing)
2. A staff member cancels a member sub in Stripe (new)
3. A staff member cancels a member sub in Admin (new)
4. A sub is canceled automatically by Stripe because of multiple failed
payments (new)
- the copy of the staff notification email has also been updated to take
into account 1) manual vs automatic cancellations, and 2) immediate vs
end of billing period cancellations
