Separate 'delete permanently' and 'access trashed contacts'

As per Brian Shaughnessy's comment to CRM-6806:

It would be useful to distinguish the two delete functions more clearly via permissions. For example:

— Delete to Trash
— Delete Permanently
— Access Trashed Contacts

One may want to define a role that can delete to trash and then view and restore those contacts (access trashed contacts) - but not permanently delete them. The current solution links delete permanently with accessing trashed contacts, which leaves an important usability gap.