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.
> It's certainly something to think about. For example, we use relation list for building menus quite often. Those node IDs were important to properly reference to menu items.

>> not the tool for the job ;)

Now it isn't, but at the time there wasn't any alternative :) There is a bundle from KNP that implements main menus, I've been wanting to explore it for a while now.