CollisionEnteredEvent
constCollisionEnteredEvent:EventHandle<CollisionEntered,ServerOnly,Entity>
On each entity of a pair that reports contacts, the step the two first
touch by any of their colliders, naming the other: Unity’s
OnCollisionEnter, Godot’s body_entered. It stays on the world that
emits it, so a crate pile never reaches the wire; a system that wants
pages to hear a touch emits its own event.