Special:NewFiles - ensure top text is entirely wrapped

Special:NewFiles - ensure top text is entirely wrapped

The template on commons for newimagestext has a <div> wrapper,
and trying to wrap a <p> around a <div> doesn't work: the <p> is
implicitly closed by the start of the <div>.  Use a <div> wrapper
to set the content language and directionality instead, which ensures
that it is valid HTML and will be tidied correctly.

In the process, fix an extra argument (and unnecessary optional argument)
passed to OutputPage::addWikiTextTidy in
Ife33ceed39ed01d4e9af18e9108026f341e9b343.

Bug: T205624
Change-Id: I42d198e6d03afd5b976da741f235c175bfe9f767