Bug 57416: Fix serialization of interwiki links with query string or fragment id

Use external link serialization for interwiki links if

1) the remaining part of the href contains a query string (example:
   [[:en:Foo?bar]]), or

2) the remaining part of the href is only a fragment identifier (example:
   [[:en:#bar]]).

Both are not supported in wikitext.

Change-Id: Ib4b41606f6c7e3218bf2e7c1fc7ff12f54a96d28