[User-Login] user can log in with registered email and password

# Request data
- email
- password

# Implementation
- confirm that user is registered (Users table)

# Response data
- access token: 20 mins lifetime, set in Authorization header
- refresh token: 30 days lifetime, set in cookies
- data:
-> first name
-> last name

# PS
- all tokens must be JWT with a private RSA key of size 1024
- token payload includes user id