All neutron entities are visible across all projects with Identity v3

[Nikolay Pliashechnikov]

Users encountered that Neutron with OpenContrail plugin and v3 authentication does not respect tokens' scope while giving information back to user.
As a consequence, all Neutron entities created by admin of project A will be visible to admin of project B, which can lead to Openstack malfunction if entities with same names are present in both projects.

For example:
Admin of project A creates security group named "test-secgroup". Admin of project B does the same, then admin of project B tries to boot VM:

# nova boot --image my-cirros-image --flavor m1.tiny --security-group test-secgroup --nic net-id=private-net-id
Which results in error:
ERROR (Conflict): Multiple security_group matches found for name 'test-secgroup', use an ID to be more specific. (HTTP 409) (Request-ID: req-169fab15-7e93-4a0e-a085-dfdfd89869fc)

Moreover, admin of project B is able to edit and even delete entities created by admin of project A (and vice versa), which may be a security concern.

Cross-project visibility was verified and confirmed for following Neutron entities:
- Network
- Security Group
- Router
- LB pool
Our clouds use Contrail 2.0.1 build 41 and 2.0.1 build 43. Idenitity v3 auth with LDAP backend is used.