add oauth authentication (#1681)

* add oauth authentication

Add support for OAuth2.

Change the interface to AuthTypeBase
  - better handling of config parameters
  - add a complete_setup function for additional setup steps

Added a function wrapper to enforce authentication for the
routes that require authenticaiton.

* change fsspec requirement

fsspec 0.8.0 breaks our tests
it imports a module that is does not require.

server/auth/__init__.py

@@ -4,3 +4,4 @@
 import server.auth.auth_none  # noqa: F401
 import server.auth.auth_test  # noqa: F401
 import server.auth.auth_session  # noqa: F401
+import server.auth.auth_oauth  # noqa: F401