Backport v3 multinic tests to v2

Adds tests which were only added to the v3 version of the multinic
unittests. Also renames oddly named test file. This is prep work
for a follow patch to share unittests between v2 and v2.1

Partially implements blueprint v2-on-v3-api

Change-Id: I87ad4d7bfb2f65f60d812dbe29866f28f776145f
Merge "Backport v3 multinic tests to v2"