FIX: Mark InputSystemForUI.Editor assembly as Editor-only to fix Assembly Definition Validation failure (#2454)

Author: Pauliusd01

Packages/com.unity.inputsystem/InputSystem/Editor/Plugins/InputForUI/InputSystemForUI.Editor.asmdef

@@ -5,7 +5,9 @@
         "Unity.InputSystem",
         "Unity.InputSystem.ForUI"
     ],
-    "includePlatforms": [],
+    "includePlatforms": [
+        "Editor"
+    ],
     "excludePlatforms": [],
     "allowUnsafeCode": false,
     "overrideReferences": false,