fix: Fixed compile error in 2022.2 (#2214)

* Fix compile error in 2022.2+

Author: ShadauxCat

com.unity.netcode.gameobjects/Editor/HiddenScriptEditor.cs

@@ -1,5 +1,7 @@
 using Unity.Netcode.Components;
+#if UNITY_UNET_PRESENT
 using Unity.Netcode.Transports.UNET;
+#endif
 using Unity.Netcode.Transports.UTP;
 using UnityEditor;
 
@@ -20,7 +22,7 @@ public override void OnInspectorGUI()
             EditorGUI.EndChangeCheck();
         }
     }
-
+#if UNITY_UNET_PRESENT
     /// <summary>
     /// Internal use. Hides the script field for UNetTransport.
     /// </summary>
@@ -29,6 +31,7 @@ public class UNetTransportEditor : HiddenScriptEditor
     {
 
     }
+#endif
 
     /// <summary>
     /// Internal use. Hides the script field for UnityTransport.

com.unity.netcode.gameobjects/Editor/com.unity.netcode.editor.asmdef

@@ -14,6 +14,11 @@
             "expression": "",
             "define": "MULTIPLAYER_TOOLS"
         },
+        {
+            "name": "Unity",
+            "expression": "(0,2022.2.0a5)",
+            "define": "UNITY_UNET_PRESENT"
+        },
         {
             "name": "com.unity.modules.animation",
             "expression": "",