feat(auth): various improvements to auth/oauth installers

[iamdadmin]

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

Creating as a draft so I can add some docs to this as well.

[iamdadmin]

I've checked the docs and they didn't deep-dive into the existing stubs and system, so there's nothing to really add. The comments within the new stubs should tie everything together. I am interested in doing a separate PR later to extend the authentication, authorization and oauth docs, but I will need to get a bit further on in my project before I'm confident enough with the topic. Hope the comments and current docs are sufficient for now, sending for review!