Keep the Old UI Settings page for AuthUI v1

[fungc-io]

If the project is still using the old AuthUI v1, The "Design" page should show a page similar to the original "UI Settings" page

• With "Post Login Link" and "Post Logout Link" moved to another page (see: DES-35 : Post-login/logout link and "Back to your app" link placements​)
• The page should called "Design" instead of "UI Settings"

[linear[bot]]

DEV-1394 Keep the Old UI Settings page for AuthUI v1