Change validators to use the validator_context

Change InstanceKeys to take a namedtuple for context

util/config/validators/validate_oidc.py

@@ -6,8 +6,10 @@ class OIDCLoginValidator(BaseValidator):
   name = "oidc-login"
 
   @classmethod
-  def validate(cls, config, user, user_password, app):
-    client = app.config['HTTPCLIENT']
+  def validate(cls, validator_context):
+    config = validator_context.config
+    client = validator_context.http_client
+
     login_manager = OAuthLoginManager(config, client=client)
     for service in login_manager.services:
       if not isinstance(service, OIDCLoginService):