Separate microversion test case related unit tests

This patch just separate the unit tests which are related to microversion
test cases logic and set/unset config values.

This is needed to migrate api_version_utils to lib with its unit tests.

Partially implements blueprint api-microversions-testing-support

Change-Id: Ie23ad006605882ab3e85e3d307a4f728231083cf
2 files changed