[WinUI3]Fix Windows 10 title bar borders (#36429)

* Fix borders for windows in the Settings UI

* Fix HOSTS window

* Fix Advanced Paste

* Fix Environment Variables

* Fix File Locksmith

* Fix Peek, with a caveat

* Fix Registry Preview

* Remove unused imports

* Clean up imports in OobeShellPage

* Move OSVersionHelper from Common.UI up into ManagedCommon

src/modules/EnvironmentVariables/EnvironmentVariables/EnvironmentVariablesXAML/MainWindow.xaml.cs

@@ -40,6 +40,7 @@ namespace EnvironmentVariables
             var handle = this.GetWindowHandle();
             RegisterWindow(handle);
 
+            WindowHelpers.ForceTopBorder1PixelInsetOnWindows10(handle);
             WindowHelpers.BringToForeground(handle);
 
             MainPage = App.GetService<EnvironmentVariablesMainPage>();