Fix sending a mail on missing required role

Previously, we would register an error in the login context (which is a login context because we are in the login flow) when the required role check failed. This would then lead to an email being sent when the email event listener is active, as that catches login errors by default.

Since this is not really useful for the users and might confuse them more than it helps, we decided to remove that feature.

Sadly, we loose the ability to track those failed logins in the console though, as that was triggered by that login error event as well.

Additionally, we now use failureChallenge instead of forceChallenge as that one is similar to the forceChallenge, but also counts the amount of failed events for brute force protection.

Closes #6 (closed)