This patch implements a new method specific for each quota driver
class. This method, "get_resource_count", returns the current number
of resources created in a project of a tracked resource. A tracked
resource is an instance of ``neutron.quota.resource.TrackedResource``.
This method does not count the current reservations, just the actual
resources created.
This new method, "get_resource_count", will be added to the abstract
class ``neutron_lib.db.quota_api.QuotaDriverAPI``.
This patch also fixes ``TestDbQuotaDriverNoLock``, that was using a
plugin inheriting from ``DbQuotaDriver`` instead of
``DbQuotaNoLockDriver``.
Closes-Bug: #1982962
Conflicts:
neutron/db/quota/driver_null.py
Change-Id: I2707506468cb60d93a4459ea364f1e79faa83838
(cherry picked from commit bd60f0833b)
ca96555e81