Consider adding error handling for ParseComputeOperationInfo

The call sites for `ParseComputeOperationInfo` do not provide the ability to propagate an error if `ParseComputeOperationInfo` detected one, such as a malformed URL. Consider enhancing the async get and async cancel request setting mechanism in `AsyncRestLongRunningOperation` to handle errors and refactor `ParseComputeOperationInfo` to return a `StatusOr`.