Display `logonid` in standalone MFA page

[iamucla]

The MFA standalone page does not show any identifying information. While it should be obvious to the user since they logged in via shib, it may not be very 'user friendly'. Perhaps we should show some self identifying information somewhere on the page?

[erutan]

One option would be copying the "logged in as" styling from heimdallr above the logout link in the header.

I'm not sure how critical it is vs just being able to do what they need to do on the page, but it could be useful for people quickly using shared computers.

[iamucla]

Don't believe it's critical, but small updates like that can be pushed continuously without disturbing the flow of things.