Tempest implements the microversion testing support and
that framework and interfaces have been tested by implementing
the Compute 2.2 microversion as well as by their unit tests.
Those should be stable interfaces so that can be consumed by other
projects microversion testing either in tempest or outside tempest.
To make them as stable interface, this commit moving that framework and
its interfaces to tempest/lib folder.
Adding release notes and library doc for those interface.
Partially implements blueprint api-microversions-testing-support
Change-Id: Icbdcfb4cd5b7fb1029eec035b9e0024be59c8d1f
