Feature/handle redirects
This merge improves the behavior of the extension with respect to redirections. Previously the authentication process was teared down once the resource has been fetched and any immediate redirection ended with losing all oidc data. After this merge the process is finalized only once a response with HTTP code from outside the range 300-399 is detected.
Improved cases:
- successful frontend/backend login
- rejected frontend authentication
Still opened:
- rejected backend authentication: the authentication error is not displayed on the backend login form