Commit I81748aa0e48b1275df3e1ea41b1d36a117d0097d added the l3 extension
API definition to neutron-lib, commit
I2324a3a02789c798248cab41c278a2d9981d24be rehomed the l3 exceptions and
Ifd79eb1a92853e49bd4ef028e7a7bd89811c6957 shims the l3 exceptions in
neutron.
This patch consumes the l3 API definition from neutron-lib
in prep for If2e66e06b83e15ee2851ea2bc3b64ad366e675dd
Change-Id: Ie5f87829ce55fed290bce4be933b9e2b0615be46