Provision Cognito and Create Auth Lambda

[nourshoreibah]

User Story

As a user, I want the app to be safe and authenticated

Description

Currently, we have no auth. If we were to deploy the lambdas publicly, anybody could mess with our database and we have no way of supporting a login.

This ticket is to do 2 things:

1. Provision cognito (it is an aws resource) through terraform
2. Create a new lambda function using lambda CLI with a register endpoint, linked to cognito

Acceptance criteria

• Create infrastructure/aws/cognito.tf with User Pool, Client
• Make a quick PR, get it reviewed, and merge it
• Make auth lambda with lambda cli. add the register (POST) route
• Install Cognito SDK in auth lambda
• Implement endpoint in with validation and Cognito SignUp
• Test registration with valid/invalid inputs and verify users in Cognito console