Bug 18980: Show distinction between shared and private lists in staff

Bug 18980: Show distinction between shared and private lists in staff

Just as we show this distinction in OPAC, this patch adds a type column
in the Your lists tab that displays Private or Shared. It always contains
Public in the other tab.

Test plan:
[1] Check if you see Shared for a private lists with shares in staff.
[2] Run t/db_dependent/Utils/Datatables_Virtualshelves.t

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Lee Jamison <ldjamison@marywood.edu>
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>