On restore, added a link to the parent deletion restore if any exists
on a cascading parent. Added a test to cover this case to ensure its shown.
Also tweaked default empty state message on recycle bin item list to align
with new column count.
Also done a little existing code cleanup including a getUrl helper on
the deletion items.
Related to #2682 & #2594
Tools seems to fit better since the classes were a bit of a mixed bunch
and did not always manage.
Also simplified the structure of the SlugGenerator class.
Also focused EntityContext on shelves and simplified to use session
helper.
