Login Window widget.

Delegate login control to an external widget. #74477
Login window changes #74477
[#82712] Changes to fix the load folder request.
Login window changes #79828
Merge branch '8.5-SNAPSHOT-login-window' into 8.5-SNAPSHOT-login-window-merge
Merge pull request #122 from alediator/8.5-SNAPSHOT-login-window-merge

8.5 snapshot login window merge