This is translation layer between the snapshot status (result of snapshot operation stored in the snapshot metadata file) and the current snapshot state (the state of the currently running snapshot in the cluster state). In this PR I am adding differentiation between complete and partial status but I am not differentiating between complete and partial snapshot state. Changing state is tricky to do if we want to preserve compatibility between different versions. I hope to do some refactoring of snapshot enums in 2.0.0 and address this issue there.