This commit adds Keystone audit middleware API logging to
the Neutron-API charm in versions Yoga and newer to allow users to
configure their environment for CADF compliance. This feature can
be enabled/disabled and is set to 'disabled' by default to avoid
bloat in log files. The logging output writes to
/var/log/neutron/neutron-server.log.
This commit builds on previous discussions:
https://github.com/juju/charm-helpers/pull/808.
Closes-Bug: 1856555
Change-Id: I6d4f471607b11c2a0450d74c8fd68385486ec8d9
84aec48548