Authentication: provide username/password or a keycloak access_token and get a bearer token in return.

• username: Open Food Facts user_id (not email)

• password: user password (clear text, but HTTPS encrypted)

• access_token: keycloak access_token (clear text)

A token is returned. If the set_cookie parameter is set to 1, the token is also set as a cookie named "session" in the response.

To authenticate, you can either:

• use the Authorization header with the Bearer scheme, e.g.: "Authorization: bearer token"
• use the session cookie, e.g.: "Cookie: session=token"