Migrate from Assisted Installer & cabpoa To MCE for OpenShift workload clusters

Summary

Evolution from Assisted Installer & cabpoa to MCE

Details

MCE will replace Assisted Installer in future OpenShift workload cluster deployments. The evolution needs to be done before 1.6 because Sylva won't be able to ensure upgrades from Assisted installer to MCE.

The MCE variant for Sylva OpenShift will be stripped down version of the official one and will not interfere with any Sylva management components.