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: Ic60ee47078089c59ccb09b8659422e7ad7081149
Partial-Bug: 1831972