Add metadata.ownerReferences to all created VolumeSnapshots about snapscheduler

[JohnStrunk]

In the initial design, I intentionally avoided adding an owner reference to help users avoid accidentally deleting their snapshots. They can be cleaned up in bulk by deleting based on the schedule label.

I am open to revisiting the behavior, particularly if it provides value within gitops or other cluster/application management tooling.
Adding a flag to preserve the existing behavior would be important.

[mnacharov]

Also we could implement some flag disableOwnerReferences in SnapshotSchedule resource to allow user disable this feature