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: I6deb26c10fa354f6b07b7afe52eae1034a4c0a03
Dependency: I5224a0910
Merge "Migrating all use of M.pageApi.getPageUrl to mw.util.wikiGetlink"