Bug 18214: Add check for shared or public list

Bug 18214: Add check for shared or public list

Following the idea behind bug 10865, we are only showing the permissions
when the list is shared or public.
Adding a simple test in opac-shelves here.

Note 1: Since the owner can always add or delete entries, the permissions
will not be relevant anymore for a strictly private list.

Note 2: Staff view always shows the permissions. This could have been
changed here too, but that change is far less urgent (bug 10865 did not
touch staff view and bug 18228 will rearrange permissions anyway).

Test plan:
[1] Verify on OPAC that you see the permissions for a private list with
    shares or a public list. And you do not see them for a private list
    without shares.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>