Create token-based authentication with the backend

[LucientZ]

Overview

Authentication currently only grabs information in the frontend. We want this to also be for the backend, which will involve sending access and refresh tokens across secure https endpoints.

Ideas

• Basic flow (All sent through HTTPS)
  • User signs in with google and sends backend an authorization code
  • Backend generates session and access token and sets session as http-only cookie
  • Frontend stores access token in memory state (useState). Could possibly also be an http-only cookie.
  • Frontend adds access token to headers for each request to the backend.
  • If frontend needs another access token, it calls <root>/auth/refresh with the refresh token as a cookie to the server to get another access token.