With the new ability to log in without redirecting to keycloak and reloading the page
we can now try to login on start every time.

Instead of remembering the login state in the session storage we just ask keycloak in an iframe
on start. To better describe this new behaviour rename the attribute from remember-login to try-login.

The newest keycloak library supporst a mode for doing the redirect in an iframe
with a separate page that needs to be whitelisted in keycloak.

The newer version also finally fixes the native promise bugs so we might as well
use the one from npm instead of fetching it from the keycloak server at runtime.

Move the keycloak code into its own class and try to abstract away as much as possible.

We now also react to all keycloak related events so logout, re-login etc are handled as well.