fix(FairyGUI): 修复资源句柄未释放导致的内存泄漏

在卸载资源时，如果资源句柄是YooAsset.AssetHandle类型，需要显式调用Release()方法释放句柄，避免内存泄漏

Author: AlianBlank

Runtime/FairyGUIFormHelper.cs

@@ -188,6 +188,11 @@ public override void ReleaseUIForm(object uiFormAsset, object uiFormInstance, ob
 
             if (uiFormAssetPath.IndexOf(Utility.Asset.Path.BundlesDirectoryName, StringComparison.OrdinalIgnoreCase) >= 0)
             {
+                if (assetHandle is YooAsset.AssetHandle handle)
+                {
+                    handle.Release();
+                }
+
                 m_AssetComponent.UnloadAsset(uiFormAssetPath);
             }
             else
@@ -225,4 +230,4 @@ private void Awake()
             }
         }
     }
-}
+}