Fix EZP-22735: Make {{ path( 'ez_urlalias' ) }} polymorphic

A fix for already existing issue at JIRA: https://jira.ez.no/browse/EZP-22735

Common usecase is to generate an URL to content in Relation field value.
Well, if we only pass the content, only the main location will be potentially present. But if it's not present, we obviously cannot generate a link...