Rewrite search result link to page in sitelinks

[malberts]

Partial follow-up to #3

Wikibase items in the search results need to link to a wiki page based on a specific sitelink.

[JeroenDeDauw]

We will need to specify the "site code" to Wikibase, which we need to have in our configuration.

I expect something like this to work

Title::newFromText( SiteLinkLookup::getSiteLinksForItem( new ItemId( 'Q123' ) )[$siteCodeFromOurConfig]->getPageName() )

• Need to get SiteLinkLookup instance
• Need to ensure the correct namesaces title is constructed when getPageName returns Person:172415