Extending quota support for neutron LBaaS entities

Note: This change is a continuation of abandoned
      change https://review.openstack.org/#/c/58720/
      Previous change was abandoned due to rebase problem.

Extending quota mechanism to support neutron
LBaaS entities. Adding quota for vips, pools, members
and health monitors.

This is one of four changes related to the BP.
This one is for neutron project.
Another one is for python-neutronclient package,
another one for tempest,
and another one for horizon/openstack-dashboard project

See blueprint neutron-quota-extension for another two changes.

Change-Id: I64a1d3647a4eb21833266346377416638667a931
Implements: blueprint neutron-quota-extension
Merge "Extending quota support for neutron LBaaS entities"