Create a dummy login API

[jayasanka-sack]

You might need a new controller and a service to do handle authentication. (something like AuthController)

Create an endpoint to login (ex /auth/login). You don't need to implement session related stuff. For now, implement something like this:
A user may provide a username and password.

• If the username and password are correct, return a 200 response.
• If the credentials are wrong, send 401.
• if the request payload is incomplete, send 400