Migrating all use of M.pageApi.getPageUrl to mw.util.wikiGetlink

mediawiki.util is loaded by deafult on mobile in the head, so there's
no reason we need to have our own function for URL retrieval.

Explicitly declaring dependancy in mobile.stable.common (although
it's loaded anyway).

Marking M.pageApi.getPageUrl as deprecated (should be removed at some
point along with related unit tests).

Change-Id: Ib3685d297fe8d6c175c5b42902e4eacac072dcec
Dependency: I5224a0910