Add support for API microversions in Tempest tests

This adds support for testing Ironic API microversions, specified
as an additional 'X-OpenStack-Ironic-API-Version' header. This change
also adds tests for Ironic API /v1/nodes/(node_ident)/states/*
endpoint for microversions that were changing state machine.

Co-Authored-By: Vladyslav Drok <vdrok@mirantis.com>
Change-Id: Ibf0c73aa6795aaa52e945fd6baa821de20a599e7
7 files changed