Unable to get security group quota numbers

[tom king]

Background:
python-openstackclient does not report the correct quota usage for security groups.
https://bugs.launchpad.net/python-openstackclient/+bug/1632460

This bug contains a comment, "No such current way to retrieve this information from the Neutron API."
https://bugs.launchpad.net/python-openstackclient/+bug/1632460/comments/1

A similar bug in python-novaclient contains a comment, "The security_group quota and usage in nova is only related to security groups created with nova-network. When using neutron, the quotas and usage are handled by neutron, not nova."
https://bugs.launchpad.net/python-novaclient/+bug/1731323/comments/4

Wishlist:
Assuming these are still correct, please add a method to retrieve security group quota usage in the Neutron API for the openstack client to use.