Add UI for explaining move to management console #1617

Created by: francisschmaltz

Create a UI that explains the move to management console for core configuration and gives users explanation of missing config. Fixes #1617 (closed) Fixes #1437 (closed)

• Removes option to configure auth providers in auth UI
• Shows notification on site-admin and site-admin configuration pages
• Removes references to configure auth providers in configuration page.

Also fixes #1437 (closed)