feat: IPhysicsEngine2D.StepIndividual method for individual object simulation

Engine.Physics2D/Abstract/IPhysicsEngine2D.cs

@@ -26,6 +26,13 @@ public interface IPhysicsEngine2D
     /// <param name="deltaTime">The time step.</param>
     void Step(float deltaTime);
 
+    /// <summary>
+    /// Advances the physics simulation by the specified time on a single <see cref="IRigidBody2D"/>.
+    /// </summary>
+    /// <param name="rigidBody">The <see cref="IRigidBody2D"/> to be progressed individually.</param>
+    /// <param name="deltaTime">The time step.</param>
+    void StepIndividual(IRigidBody2D rigidBody, float deltaTime);
+
     delegate void PhysicsIterationEventHandler(IPhysicsEngine2D sender, float iterationDeltaTime);
     delegate void PhysicsStepEventHandler(IPhysicsEngine2D sender, float stepDeltaTime);
 }