Set up Cognito user pool

=== Basic AWSCloudFormation ============

https://github.com/awslabs/aws-cognito-apigw-angular-auth/blob/master/sam/sam.yaml

====== Cognito User Pool Settings =======

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-cognito-identitypool.html#aws-resource-cognito-identitypool-syntax

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-cognito-userpool.html#aws-resource-cognito-userpool-syntax

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-cognito-userpoolclient.html

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-cognito-identitypoolroleattachment.html

================ Add group to user ============

https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/CognitoIdentityServiceProvider.html#adminAddUserToGroup-property


https://stackoverflow.com/questions/37108120/how-do-i-use-cloudformation-resources-in-a-lambda-function