Add keystone oidc tests

This adds tests to test getting a token (scoped and unscoped) when
keystone is configured to use oidc for authentication.  The oidc
provider is keycloak.  This is based in very large part on Kristi's
work in [1] and [2].

[1] https://github.com/knikolla/devstack-plugin-oidc
[2] https://github.com/CCI-MOC/onboarding-tools

Co-Authored-By: David Wilde <dwilde@redhat.com>
Change-Id: I1772b65f1cc3830ac293a800a79d044a6ab69d65
5 files changed