Dynamic rigid body on a Cube

Convenience composition: one Cube prim that is both the body and its only collider. Owns no columns; everything comes from the listed components.

• Type: Cube

• Required APIs: PhysicsRigidBodyAPI, PhysicsCollisionAPI

• Optional APIs: PhysxRigidBodyAPI, PhysxCollisionAPI, PhysicsMassAPI, MaterialBindingAPI, PhysicsFilteredPairsAPI

• Helper: create_rigid_body_cubes()