ARP spoofing patch: Data structures for rules.

ARP spoofing patch: Data structures for rules.

ARP cache poisoning is not actually prevented by the firewall
driver 'iptables_firewall'. We are adding the use of the ebtables
command - with a corresponding ebtables-driver - in order to create
Ethernet frame filtering rules, which prevent the sending of ARP
cache poisoning frames.

The complete patch is broken into smaller patch sets for easier review.

This patch set here includes the some classes for the maintenance of ebtable
chains and rules.

Note:
    This commit is based greatly on an original, now abandoned patch,
    presented for review here:

        https://review.openstack.org/#/c/70067/

Full spec can be found here: https://review.openstack.org/#/c/129090/

SecurityImpact

Change-Id: I3c66e92cbe8883dcad843ad243388def3a96dbe5
Implements: blueprint arp-spoof-patch-ebtables
Related-Bug: 1274034
Co-Authored-By: jbrendel <jbrendel@cisco.com>