Determine the infrastructure provider of the Cluster when the `infrastructureRef` is not set

[Jont828]

The app uses the kind of the cluster.spec.infrastructureRef to parse the name of the provider, i.e. Azure, AWS, GCP. Clusters built from ClusterClasses do not have it set initially and so we can't determine the provider until it is set. I'd like to find a consistent/uniform way to determine the infra provider so the icon is always set correctly.