KinematicBody2D does not exist in 4.0 and move_and_slide has changed

**Your Godot version:**
4.0 beta1

**Issue description:**
https://docs.godotengine.org/en/latest/tutorials/physics/physics_introduction.html?highlight=move_and_slide#move-and-slide

`KinematicBody` should be changed to match the new `CharacterBody3D`

Especially important is the `move_and_slide` function, which seems the most common way to move gameobjects in 3.x branches, yet has changed in 4.0 and a migrating user has no idea how to achieve simple movement.