[FEATURE] Add authentication matching rule to router

For protected pages, a custom matching rule is needed that ensures that the current user is properly authenticated. See [here](https://github.com/auraphp/Aura.Router/blob/3.x/docs/defining-routes.md#authentication) and [here](https://github.com/auraphp/Aura.Router/blob/3.x/docs/custom-matching.md) for implementation details.
