Migrate Rails Guides from `Turbolinks` to `Turbo`

[marcoroth]

Summary

This Pull Requests updates the Rails Guides to use Turbo.

Rails 7 ships with Turbo by default and I think it makes sense if the official Rails guides also used Turbo instead of the now deprecated Turbolinks.

Other Information

This Pull Request is basically the spiritual successor of https://github.com/rails/rails/pull/32405.