Core API AEAD Cipher

[officialfrancismendoza]

Basing off feature/symmetric-cipher branch, establish AEADCipherEncryptor and AEADCipherDecryptor in a similar manner to BlockCipherEncryptor and BlockCipherDecryptor.

To be used for the ASCON lowmemory derivative later, as well as subsequent features.

[ounsworth]

And to be used by the AES_GCM mode that David is working on.

[dghgit]

Actually, Francis is now doing GCM, I seem to have run out of time, and tokens!

@officialfrancismendoza Francis I had another look at the OpenSSL list, add CCM as well, it's probably a good one to include for other reasons, as it's more a packet cipher than a streaming cipher so it will flush out any issues with the way the AEAD encryptor/decryptor traits are defined that might prevent us from supporting it.