[Pages listing] The default WF pages come without a slug

**Describe the bug**
When going to view one of the published default pages (i.e., Home, T&C, Policy) from the page listing, you are directed to the public website by using the ID of the page instead of the slug. So, if the slug is `/home` and the page ID is `1`, you should be directed to `website-factory.test/en/home` but are taken to `website-factory.test/en/1`, which does not exist.

This seems to happen because the generated pages do not have a slug themselves.

**To Reproduce**
Steps to reproduce the behavior:
1. Log into the admin interface of a new WF instance
2. Go to '/admin/pages'
3. Locate one of the published default pages (i.e., Home, T&C, Policy) before they are modified
4. Click on the down arrow next to a page
5. Click on `View`/`Vezi`
6. You are directed to a 404 page with the URL `//`

**Expected behavior**
You should be directed to a page with the slug `//`

**Screenshots**
Clicking on the view button...

... directs you to an address with the page ID...