Support custom name of volumeClaimTemplates for statefulSet deployments

[chringwer]

While we have deployment properties to specify size and class of the volumeClaimTemplate for a stateful set (statefulSet.volumeClaimTemplate.storageClassName and statefulSet.volumeClaimTemplate.storage), there doesn't seem to be a way to specify the template's name. Instead it is hardcoded to be the appId.

Now, in order to really make use of the persistent storage, we would need to add a volumeMount referencing the template by name. When deploying via Spring Cloud Dataflow, I have not been able to figure out a way to predictably infer the appId upfront. Am I missing something?

I would like to suggest something like statefulSet.volumeClaimTemplate.name so that we have a way to deterministically reference it in a volumeMount.