Prepare crypto framework for IPsec ESN support

This permits requests (netipsec ESP and AH protocol) to provide the
IPsec ESN (Extended Sequence Numbers) in a separate buffer.

As with separate output buffer and separate AAD buffer not all drivers
support this feature. Consumer must request use of this feature via new
session flag.

Submitted by: Grzegorz Jaszczyk <jaz@semihalf.com>

Patryk Duda <pdk@semihalf.com>

Reviewed by: jhb
Differential revision: https://reviews.freebsd.org/D24838
Obtained from: Semihalf
Sponsored by: Stormshield