Merge pull request #16082 from juanvallejo/jvallejo/ensure-unstructur…

…ed-objects-before-composing

Automatic merge from submit-queue

UPSTREAM: 51727: ensure oc get deals with unstructured resources

Fixes #16064
Addresses BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1487245

`$ oc get ...` assumed all resources returned from a resource builder were unstructured objects.
This patch ensures we are dealing with unstructured objects before attempting to
compose into an unstructured list.

cc @openshift/cli-review @enj