`openshift-tests images` identifies the locations of all test images referenced by the test suite and outputs a mirror list for use with 'oc image mirror' to copy those images to a private registry.

Additionally, there's a LocationFor helper in origin that when using such a mirrored repository will rewrite the pullspec.

We need to be able to support extension binaries providing their own images, and consuming the mirrored images.

Some work was already done to work for k8s-tests-ext, although it's a special case since kube has their own helper for image locations, and learns about image mirroring through environment variables.  I would prefer if OTE took a different approach.

Acceptance criteria:

• OTE has an images subcommand [done - https://github.com/openshift-eng/openshift-tests-extension/pull/20]
• `openshift-tests images` subcommand queries all extension binaries for images [done - https://github.com/openshift/origin/pull/29450]
• When origin executes a test, it passes in `--mirrored-images` or similar with a pointer to a JSON or other serialized data that references the mirrored pull specs
• OTE has a LocationFor helper that uses the passed in mirrored images data to return the actual or real pullspec.