Update cluster-machines-ready with OpenShift update status check

OpenShift update through the openshift agent CAPI provider will be triggered by changing distributionVersion ( https://github.com/openshift-assisted/cluster-api-agent/blob/41e2533dd2d4f53b4fb0366e437a43a6cf04490b/controlplane-components.yaml#L234).

Core CAPI will be unaware of this in-place upgrade activity; so the controlplane .status.replicas, .status.updatedReplicas won't change during the update process, and condition=Ready will always be true (if nothing bad happens to the upgrade).

We are going to use a condition=UpgradeCompleted test to decide if the upgrade (and even install ) is complete for OpenShift and reflect this in the cluster-machines-ready unit. So basically we will insert this test in cluster-machines-ready for openshift cluster: kubectl wait -n <..> openshiftassistedcontrolplane/<..> --for condition=UpgradeCompleted

@tmmorin @cristian.manda @feleouet what's your opinion before we move along on this path with the CAPI upgrade implementation and eventually submit an MR to update the cluster-machines-ready as mentioned above?

Also any other Sylva units may need similar update status handling?

I'd like to keep the discussion here than the slack for better documentation history