1,fix ImageLoader GetIcon() trigger FileNotFoundException when file not exist;

2,In FolderPluginSettings when trigger Delete Action need confirm;
3,Add drag and drop functionality in ProgramSetting and FileSystemSettings.

Signed-off-by: 716 <525223688@qq.com>

Wox/ImageLoader/ImageLoader.cs

@@ -37,6 +37,8 @@ namespace Wox.ImageLoader
 
         private static ImageSource GetIcon(string fileName)
         {
+            if (System.IO.File.Exists(fileName) == false) return null;
+
             Icon icon = GetFileIcon(fileName);
             if (icon == null) icon = Icon.ExtractAssociatedIcon(fileName);