OperationStatus type 
Defines values for OperationStatus. 
KnownOperationStatus can be used interchangeably with OperationStatus,
this enum contains the known values that the service supports.
Know values supported by the service
Undefined: Undefined operation status. 
NotStarted: Background operation created but not started yet. 
Running: Background operation is currently running. 
Succeeded: Background operation finished with success. 
Failed: Background operation finished with failure.
type OperationStatus = string