Make base url of preview.html dynamic

Authored by Florian on Fri, May 19, 5:07 PM.

Description

Make base url of preview.html dynamic

Like the changed for index.html, the preview.html base url is not
hardcoded to wikipedia.org anymore, but set via JS from the WikiSite which
is in use for the edit preview.

Bug: T165789
Change-Id: I95510a6aa7121362d5e3f860ed161b23452204ae