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.
If I understood the issue correctly we should not recommend using id's, so a bit strange to introduce possibility for 'contentId' or?