FEP-ef61 update: https://codeberg.org/fediverse/fep/pulls/717
- Added a section explaining how to compare 'ap' URIs.
- Origin tuples are replaced with "cryptographic origins". The result is the same, but now we don't have to use port 0.
- Outboxes and FEP-ae97 are not required anymore. This means implementers can use a different activity synchronization mechanism.
