Added Auth0 authentication service

The first step was completing the Next JS + Auth0 Quickstart tutorial.

But something wasn't quite right.

I didn't have my environment variables setup properly on my production server. I'm using Vercel, so it was easy enough to setup. This allowed me to have a local and a production setup which works really well.

After that it was just a little work to create a simple user menu button.

{user ?
  <Button variant="contained" onClick={handleUserMenuClick}>{user.nickname}</Button>
  : <Button variant="contained">
    <Link href="/api/auth/login">
      <Typography variant="button" color="inherit">
        Login
      </Typography>
    </Link>
  </Button>
}