[permissions] Define underlying infrastructure (#33)

See e.g. Notifications API Standard or Storage Standard.

Specifications will need access to the underlying algorithms as to what the status of a permission is. They might also want to subscribe to change notifications as this might impact existing objects (e.g. for notifications we'd likely remove the notifications).

---
Reply to this email directly or view it on GitHub:
https://github.com/w3c/permissions/issues/33