Feature: Create User in Database upon successful Google OAuth2 Authorization

[singhmi4]

What it does

1. cd server
2. pipenv install
3. pipenv run flask run
4. go to 127.0.0.1:5500/login in web browser
5. Accept Google Account authorization
6. Inspect terminal for either of the following message:
   • "user added to database!" if email doesn't already exist
   • "user exists in database. cannot add to database" if email exists
7. Inspect terminal for the latest list of users

What to look for

• Proper import structure in app.py
• Correct OAuth2 setup and config with imports, routes, and environment variables
• Proper database implementation on lines 91 to 97 in app.py

What to avoid

• Access token entry when creating new user

[singhmi4]

This PR might not be needed anymore since I've changed the Google Oauth2 and user creation to be done on the front-end: #19