Make Cognito redirect URLs configurable in web service

[tylerthome]

Overview

Update references to the redirect URLs for Cognito in the Flask application

Action Items

• Establish a configuration convention for the Flask application, e.g. use a json or xml config format, env file
• Create the configuration for the redirect URI for HUU tenant in AWS Cognito
• Reference the configured value in all statements requiring the redirect URL

Resources/Instructions

The redirect URL tells Cognito where to send a user after authentication. The HomeUniteUs API is deployed in a variety of environments, e.g. dev-ec2, test-ec2, prod-ec2, host-local, docker-local. Each of these may have different URLs where the web service is hosted, which the app will need to specify in requests to Cognito for user management operations like token validation.