FIX: Remove errors when using UITK Asset Editor (ISX-1531) (#1723)

This avoids a breaking API change for the InputParameterEditor class.
Developers need to override this method to implement a custom UI for UITK Asset Editor.

Author: jfreire-unity

Packages/com.unity.inputsystem/InputSystem/Editor/InputParameterEditor.cs

@@ -182,6 +182,17 @@ internal override void SetTarget(object target)
             OnEnable();
         }
 
+#if UNITY_INPUT_SYSTEM_UI_TK_ASSET_EDITOR
+        /// <summary>
+        /// Default stub implementation of <see cref="InputParameterEditor.OnDrawVisualElements"/>.
+        /// Should be overridden to create the desired UI.
+        /// </summary>
+        public override void OnDrawVisualElements(VisualElement root, Action onChangedCallback)
+        {
+        }
+
+#endif
+
         /// <summary>
         /// Helper for parameters that have defaults (usually from <see cref="InputSettings"/>).
         /// </summary>