fix(items): qualify System in the culture scope of Get-ChildItem2

The class has the parameter System, so a name that starts with System resolves
to the property inside it; the build of the previous commit failed with CS0120.
The scope uses global::System, like the rest of the file.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: AI Assistant <ai@example.com>

NTFSSecurity/ItemCmdlets/GetChildItem2.cs

@@ -388,17 +388,17 @@ namespace NTFSSecurity
 
         private sealed class InvariantCultureScope : IDisposable
         {
-            private readonly System.Globalization.CultureInfo previous;
+            private readonly global::System.Globalization.CultureInfo previous;
 
             public InvariantCultureScope()
             {
-                previous = System.Threading.Thread.CurrentThread.CurrentCulture;
-                System.Threading.Thread.CurrentThread.CurrentCulture = System.Globalization.CultureInfo.InvariantCulture;
+                previous = global::System.Threading.Thread.CurrentThread.CurrentCulture;
+                global::System.Threading.Thread.CurrentThread.CurrentCulture = global::System.Globalization.CultureInfo.InvariantCulture;
             }
 
             public void Dispose()
             {
-                System.Threading.Thread.CurrentThread.CurrentCulture = previous;
+                global::System.Threading.Thread.CurrentThread.CurrentCulture = previous;
             }
         }
     }