allow mark localpv-provisioner as default StorageClass

[developer-guy]

There is an option of changing the default StorageClass in Kubernetes clusters, and this is as easy as adding a specific annotation to the StorageClass, you can see from the following link below 👇:

👀 https://kubernetes.io/docs/tasks/administer-cluster/change-default-storage-class/

We (w/@Dentrax @eminaktas @erkanzileli) thought that it would be nice to have an option to enable this support via the localpvprovisioner section in values.yaml.

👀 https://github.com/openebs/charts/blob/main/charts/openebs/values.yaml#L95