performStage

abstract fun performStage(    flowResponse: RegistrationFlowResponse,     errCode: String?,     promise: Continuation<UIABaseAuth>)

When the API needs additional auth, this will be called. Implementation should check the flows from flow response and act accordingly. Updated auth should be provided using promise.resume, this allow implementation to perform an async operation (prompt for user password, open sso fallback) and then resume initial API call when done.