Extend the starlette simple user

[signebedi]

Right now, the starlette simple user only stores the username. But, in order to minimize the number of database queries, perhaps we can store a little more - like the user ID and API key...

Originally posted by @signebedi in #19 (comment)

[signebedi]

See source at https://github.com/encode/starlette/blob/master/starlette/authentication.py:

class BaseUser:
    @property
    def is_authenticated(self) -> bool:
        raise NotImplementedError()  # pragma: no cover

    @property
    def display_name(self) -> str:
        raise NotImplementedError()  # pragma: no cover

    @property
    def identity(self) -> str:
        raise NotImplementedError()  # pragma: no cover


class SimpleUser(BaseUser):
    def __init__(self, username: str) -> None:
        self.username = username

    @property
    def is_authenticated(self) -> bool:
        return True

    @property
    def display_name(self) -> str:
        return self.username


class UnauthenticatedUser(BaseUser):
    @property
    def is_authenticated(self) -> bool:
        return False

    @property
    def display_name(self) -> str:
        return ""