Work on login/sign up flow

[Kerushani]

• Currently, there is a way to create, update, delete, and read users on the platform.
• The signup flow is not yet concrete. It still has some work to do. Maybe look at using other tools to learn something new.
• The db is not up and running properly so get that working as well.

[Kerushani]

• Merge pull request Set up sign up flow #14 -- sets up the endpoints for register + login + refresh tokens
• Still need to integrate it into the frontend