Add "Virtual View" icon to faceted folders

See screenshot.
The "tags" and "state" folders are virtual folders, so they should get a slightly different icon that tells the user this is not a physical folder.

"unpublished" / "draft" / "published" need a virtual folder icon too. This could be the same icon, unless it's possible to tell them apart from their parents, in which case it would be nice to have a different icon for facetvalues.