GetQuotedString() uses correct windows cmdline notation

- escaping of backslash and quotes
- fixes gh-312 for new cmdline parser algorithm (gh-307, gh-310)

Signed-off-by: Sergey G. Brester <info@sebres.de>
Reviewed-by: Tino Reichardt <milky-7zip@mcmilk.de>

CPP/7zip/UI/Explorer/ContextMenu.cpp

@@ -408,7 +408,8 @@ static UString GetQuotedReducedString(const UString &s)
   UString s2 = s;
   ReduceString(s2);
   s2.Replace(L"&", L"&&");
-  return GetQuotedString(s2);
+  s2.InsertAtFront(L'"'); s2 += L'"'; // quote without GetQuotedString (because it escapes now)
+  return s2;
 }
 
 static void MyFormatNew_ReducedName(UString &s, const UString &name)