Add authentication for users accessing the FastAPI server

[bhavya-tech]

Currently all the endpoints of FastAPI server are open. We should add an authentication layer which will protect these endpoints from unauthorised access.

Points to consider:

• Keep it optional. Because on local dev server it will be hassle.
• If we are using just username and password, where will it be stored securely? Adding this means the docker container will be stateful.
• Oauth2 implementation can be done.