WIP: always show folders which don't have unread entries but which contain a feed with a job state alert in the start page.
Fixed function used to filter visible folders.

Specifically, controlled the case in which the root scope contains no feeds in the passed folder. This was not properly controlled and caused the logic to fail in many causes, with unwanted results (folders not becoming visible or the opposite).
A folder without unread entries but which contains a feed with a refresh job state alert in the start page, will be shown.