Prepare crypto framework for IPsec ESN support

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