Implement cloud-config-file flag in CCCMO render

--config-file flag is required by Azure and Azure Stack Hub CCM. 

This flag would point to cloud-config configMap file generated by cluster-config-operator in bootstrap. The data would be unpacked from the configMap and the raw content should be copied to /etc/kubernetes/bootstrap-secrets, where it could be mounted in a hostPath volume.

Static pods can't mount ConfigMaps directly: https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap/#restrictions

DoD:

• Implement --cloud-config-file flag in CCCMO render binary.
• ConfigMap would be read, unpacked and placed to `./config` directory as `./config/cloud.conf`.
• Installer implementation in https://github.com/openshift/installer/pull/4947 will copy `./config/*` to `/etc/kubernetes/bootstrap-configs/` folder.