(GH-853) Prompt for choice split

Do not remove empty entries in the case of prompt for choice, which is
determining if a string contains `&` so it can build the labels
properly.

This is a partial reversion of what was introduced by 401335b.

src/chocolatey/infrastructure/powershell/PoshHostUserInterface.cs

@@ -178,7 +178,8 @@ public override void WriteWarningLine(string message)
         private static string[] get_hotkey_and_label(string input)
         {
             var result = new[] { String.Empty, String.Empty };
-            string[] fragments = input.Split(new char[] {'&'}, StringSplitOptions.RemoveEmptyEntries);
+            //Do not use StringSplitOptions.RemoveEmptyEntries, it causes issues here
+            string[] fragments = input.Split('&');
             if (fragments.Length == 2)
             {
                 if (fragments[1].Length > 0) result[0] = fragments[1][0].to_string().ToUpper(CultureInfo.CurrentCulture);