feat: change the character controller’s solve_character_collision_impulses to take multiple CharacterCollision (#646)

* character controller: solve multiple collisions

* add solve multiple collisions to changelog

* chore: apply review comments

---------

Co-authored-by: Sébastien Crozet <sebcrozet@dimforge.com>

src_testbed/testbed.rs

@@ -811,19 +811,16 @@ impl<'a, 'b, 'c, 'd, 'e, 'f> Testbed<'a, 'b, 'c, 'd, 'e, 'f> {
                 QueryFilter::new().exclude_rigid_body(character_handle),
                 |c| collisions.push(c),
             );
-
-            for collision in &collisions {
-                controller.solve_character_collision_impulses(
-                    phx.integration_parameters.dt,
-                    &mut phx.bodies,
-                    &phx.colliders,
-                    &phx.query_pipeline,
-                    character_collider.shape(),
-                    character_mass,
-                    collision,
-                    QueryFilter::new().exclude_rigid_body(character_handle),
-                )
-            }
+            controller.solve_character_collision_impulses(
+                phx.integration_parameters.dt,
+                &mut phx.bodies,
+                &phx.colliders,
+                &phx.query_pipeline,
+                character_collider.shape(),
+                character_mass,
+                collisions,
+                QueryFilter::new().exclude_rigid_body(character_handle),
+            );
 
             let character_body = &mut phx.bodies[character_handle];
             let pos = character_body.position();