Replace Kiss3d by Bevy for the testbed renderer.

examples3d/debug_prismatic3.rs

@@ -103,8 +103,3 @@ pub fn init_world(testbed: &mut Testbed) {
     testbed.set_world(bodies, colliders, joints);
     testbed.look_at(Point3::new(10.0, 10.0, 10.0), Point3::origin());
 }
-
-fn main() {
-    let testbed = Testbed::from_builders(0, vec![("Boxes", init_world)]);
-    testbed.run()
-}