Support for ```openpgp-s2k3-ocb-aes``` private key protection with openssl backend

[maxirmx]

Implement support for openpgp-s2k3-ocb-aes private key protection with openssl backend. This feature is used in GnuPG 2.3+ extended key format and is supported/tested with Botan backend.

With openssl backend an attempt to set AAD used by GbuPG causes padding check failed openssl error.

This is a backlog from (#1949, #1724)