As a cluster administrator i want to migrate my current homogeneous cluster to a heterogeneous cluster by upgrading to a heterogeneous manifestlisted payload so i can add mixed architecture workers from thereon.

We would have a command to the effect of `oc adm upgrade migrate-arch` which would migrate the cluster to a heterogeneous payload. An architecture property would also be introduced in the ClusterVersion spec and possibly status to indicate that the cluster supports heterogeneous nodes. 

Refer to discussion: https://coreos.slack.com/archives/CEGKQ43CP/p1646756387872329 and enhancement: https://github.com/openshift/enhancements/pull/1014