Enable support for configuration of FWaaS v2 firewall group
logging.
Configuration options mirror those for neutron-openvswitch
for security group logging.
This feature is currently only enabled for FWaaS v2 at Stein
for the charms (but is supported back to Queens in Neutron).
Change-Id: If1b332eb0f581e9acba111f79ba578a0b7081dd2
Partial-Bug: 1831972