ShapeHitbox.allowSiblingCollision could be moved into broadphase

[ASGAlex]

What could be improved

Ideally, we cah check allowSiblingCollision at broadphase, before creating unnecesary CollisionProspect for siblings pairs. And skip several iterations over "potentials" list later.

Why should this be improved

A little bit better performance.

Any risks?

Every broadphase implementation should implement it's unique "siblings check". An interface could be added for that.