EZEE-3506: Added data for SiteFactory setup

[mnocon]

JIRA: https://issues.ibexa.co/browse/EZEE-3506

Required by:
https://github.com/ezsystems/ezplatform-site-factory/pull/116

Things done:

1. ConfigurationEditor is now a bit smarter:
   you can use a special %location_id(itemLocationURL)% function which will be resolved to the location_id of the specified item.

Example:

  Scenario Outline: Configure Site Factory siteaccesses
    Given I append configuration to "ez_platform_site_factory.templates" in "config/packages/ezplatform_site_factory.yaml"
    """
          <template_id>:
            siteaccess_group: <sa_group>
            name: <template_name>
            thumbnail: https://placekitten.com/500/500
            site_skeleton_id: "%location_id(Site-skeletons/MySiteSkeleton)%"
    """

The site_skeleton_id value will be set to the Location ID of the /Site-skeletons/MySiteSkeleton item. No need for hardcoding IDs 😄

2. Added Twig templates required by https://github.com/ezsystems/ezplatform-site-factory/pull/116 (more description there).

[bogusez]

I would add an empty line at the end of the file

[mnocon]

Enabled and fixed CS for tests in 9825288