feat(auth): add various improvements to auth and oauth installer

[iamdadmin]

(Replaces PR 1900 with clean code...)

Closes #1888 various improvements to auth/oauth installers, as follows

• (Installer) Asks whether to install OAuth first and provides different UserModel and Migration stubs with pre-populated fields matching the OAuthController
• Adds a very basic MustBeAuthenticated middleware stub, I've tested it in my own app, it's something that can be built upon but should give a working system
• Adds a very basic LoginController stub to show the login view (view NOT PROVIDED, comment explains this), post login (database query NOT PROVIDED, comment explains this), handle logout
• Implements Tempest\Http\Session\PreviousUrl to set/get the intended URL and redirect there after auth
• Update installer tests for revised questions/answers format