Refactor integrated tests to support V2 and V3 API testing Part 2

This changeset moves the APISampleTestBase class out into its own
file so the V3 versions of the tests can cleanly import it separate
from the V2 code.

Partially implements v3-api-unittests
Partially implements v3-api-specification

Change-Id: If0994934edb2ab19004353f9a4089ce525ed31dd
Merge "Refactor integrated tests to support V2 and V3 API testing Part 2"