Rails 8 adds built in authentication generator

Now built a little workplace internal tool that needed a login page with it! Honestly pretty satisfied, it's simple enough that 10minutes is all you need to understand how it works: incredibly boring and standard (/pos)

My one gripe, that I think I might offer up a PR for, is it should have generators for log-in minitest helpers. You will end up making a log_in_as(user) method that sets the auth session cookie anyway... might as well just have that from the start.

The lack of registration also does feel weird to me as well. I know that user registration is probably the most variable part of the auth process, but stuff scaffolded from Rails is normally very delete-friendly anyway. Plus, 9/10 this generator is being run on a new project, so I immediately need to build it anyway, so I can set up system tests that log in and such.