Fixes when New Input System is not present

Runtime/Input/InputSystemUtility.cs

 #if ENABLE_INPUT_SYSTEM
 using UnityEngine.InputSystem;
 using UnityEngine.InputSystem.Controls;
+#endif
+#if ENABLE_INPUT_SYSTEM
         public static ButtonControl GetButton(MouseButton b)
         {
             Mouse m = Mouse.current;

Runtime/LevelScripting/Events/OnInputDirectEvent.cs

     [AddComponentMenu(ComponentMenu.eventsPath + "On Input Direct Event (New Input System)")]
     public class OnInputDirectEvent : EventBase
     {
+#if ENABLE_INPUT_SYSTEM
         [SerializeField]
         Device device = Device.Keyboard;
         [SerializeField, ShowIf("IsMouse")]
         [SerializeField, ShowIf("IsKeyboard")]
         Key keyboardKey = Key.Space;
 
+        bool IsMouse() => device == Device.Mouse;
+        bool IsGamepad() => device == Device.Gamepad;
+        bool IsKeyboard() => device == Device.Keyboard;
+#endif
-        bool IsMouse() => device == Device.Mouse;
-        bool IsGamepad() => device == Device.Gamepad;
-        bool IsKeyboard() => device == Device.Keyboard;
+
-        ButtonControl button;
+        ButtonControl button;
 
         private void OnEnable()
         {

Runtime/Managers/Implementations/UIEventManager.cs

 #if ENABLE_INPUT_SYSTEM
 using UnityEngine.InputSystem;
 using UnityEngine.InputSystem.UI;
-using UnityEngine.UI;
+using UnityEngine.UI;
 
 namespace GameplayIngredients
 {