Slightly rework shouldUseToUnicodeEx to avoid errors (#17334)
shouldUseToUnicodeEx can sometimes result in none object has no property helperLocalBindingHandle error. This is hard to reproduce but I've seen it often in WhatsApp UWP.
Description of user facing changes
None known.
Description of development approach
When checking for helperLocalBindingHandle, ensure that appModule has a value.
While at it, reorder the checks, since in current era, UWP applications are much more common than during the initial implementation of this approach.
