Change default action for authentication annotation

[aledbf]

If the Ingress contains an auth rule block all the traffic until the requirements are met (for instance an inexistent secret)

[ConnorJC3]

+1

[groob]

Would it be possible to support an authentication page for 401 errors? Similar to the example here
https://github.com/bitly/oauth2_proxy#configuring-for-use-with-the-nginx-auth_request-directive

[ConnorJC3]

@groob A separate issue might be better for that