win32_utf8: Add CreateDialogParam and DialogBoxParam.

Bravo, Microsoft. What a great design.

If you just replaced lpTemplateName with an integer parameter (I mean, who references dialog box templates by name anyway), we wouldn't have needed the entire A and W distinction for these, because dialog box templates are guaranteed to be UTF-16 anyway.

And since everyone uses MAKEINTRESOURCE anyway, there is no reason to use the A version *at all*, even if you wouldn't code in Unicode otherwise (which, really, you should have done from the start, but oh well).