Fixed issue where set as options wouldn't show for images (#4455)

Author: winston-de

Files/BaseLayout.cs

@@ -474,6 +474,7 @@ public void BaseContextFlyout_Opening(object sender, object e)
 
         private void LoadMenuItemsAsync()
         {
+            SelectedItemsPropertiesViewModel.CheckFileExtension();
             var shiftPressed = Window.Current.CoreWindow.GetKeyState(VirtualKey.Shift).HasFlag(CoreVirtualKeyStates.Down);
             var items = ContextFlyoutItemHelper.GetItemContextCommands(connection: Connection, currentInstanceViewModel: InstanceViewModel, workingDir: ParentShellPageInstance.FilesystemViewModel.WorkingDirectory, selectedItems: SelectedItems, selectedItemsPropertiesViewModel: SelectedItemsPropertiesViewModel, commandsViewModel: CommandsViewModel, shiftPressed: shiftPressed, showOpenMenu: false);
             ItemContextMenuFlyout.PrimaryCommands.Clear();

Files/ViewModels/SelectedItemsPropertiesViewModel.cs

@@ -539,14 +539,14 @@ public bool IsSelectedItemShortcut
             set => SetProperty(ref isSelectedItemShortcut, value);
         }
 
-        public async void CheckFileExtension()
+        public void CheckFileExtension()
         {
             // Set properties to false
             IsSelectedItemImage = false;
             IsSelectedItemShortcut = false;
 
             //check if the selected item is an image file
-            string ItemExtension = await CoreApplication.MainView.ExecuteOnUIThreadAsync(() => contentPage?.SelectedItem?.FileExtension);
+            string ItemExtension = contentPage?.SelectedItem?.FileExtension;
             if (!string.IsNullOrEmpty(ItemExtension) && SelectedItemsCount == 1)
             {
                 if (ItemExtension.Equals(".png", StringComparison.OrdinalIgnoreCase)