Added --wikidb param to sql.php (backport to wmf6)

* This is useful for updating DBs that are not actually a that of a wiki.
  For example a global blocking or central auth DB may not correspond to
  any single wiki. Trying to use --wiki will fail with het deploy

Bug: 58351
Change-Id: I232182b79c9ca6421789f19771ba427498fff713