DEV-16369: Refactor `objects-catalog.webc` to render ALL objects in `/content/`

[anderspollack]

This refactor changes the behavior of layout: objects-page (objects-catalog.webc) to render all objects in project, regardless of where layout: objects-page is located in the /content/ directory.

We didn't originally implement it this way as we assumed we could have multiple directory-specific objects-page layouts in the same project (which currently does not work - the objects of the first instance of an objects-page get displayed in all instances). But this should fix the immediate issue