Add new auth configuration options

[leitgab]

There are new auth configuration options oauth_auto_login and signout_redirect_url available as mentioned in the appropriate chapter of documentation:
https://grafana.com/docs/auth/overview/

Please add mentioned options, because they are necessary for useful implementation of OAuth/SSO.

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.