Change function signature to implement the algorithm in the logout handler instead of extending main get function.
Change function signature to implement the algorithm in the logout handler instead of extending main get function.

Call the AWS Cognito API as described in https://docs.aws.amazon.com/cognito/latest/developerguide/logout-endpoint.html

Use native coroutines instead

Fix auth_state is not cleared before logout

jupyterhub/oauthenticator,minrk/oauthenticator,NickolausDS/oauthenticator