Include AEAD
This series brings in just the AEAD packet from the older draft-ietf-openpgp-rfc4880bis-10
, without SKESK, preferences, etc. Hopefully we can use this MR to discuss just the AEAD format on its own; when that is resolved, we can work to incorporate appropriate SKESK, preferences, etc.
Note that the test vectors are supplied with just a raw key, so while it isn't really completely usable on its own, this changeset should help us focus on the AEAD mechanism specifically.