Method to retrieve an alternate AuthorizationCheckerFactory when the current AuthorizationChecker is required to process a nested AuthzRequest of a different type.
AuthzRequests can nest other AuthzRequests of different types internally. When an AuthorizationChecker finds a nested request of a different type from which it was coded to process, it uses the AuthorizationCheckerFactory to retrieve an alternate AuthorizationChecker it can chain to process the nested request.