This PR adds new collision lifecycle convenience methods to `Actor`! This was possible before by wiring up an event handler. This is a super common pattern so now it's moved to Actor!

```typescript
class MyActor extends ex.Actor {
  constructor(args: ex.ActorArgs) {
    super(args);
  }
  onPreCollisionResolve(self: ex.Collider, other: ex.Collider, side: ex.Side, contact: ex.CollisionContact): void {
    
  }
  onPostCollisionResolve(self: ex.Collider, other: ex.Collider, side: ex.Side, contact: ex.CollisionContact): void {
    
  }
  onCollisionStart(self: ex.Collider, other: ex.Collider, side: ex.Side, contact: ex.CollisionContact): void {
    
  }
  onCollisionEnd(self: ex.Collider, other: ex.Collider): void {
    
  }
}
```