LP1956619 Holdings editor sanity check for VIEW_USER perm

LP1956619 Holdings editor sanity check for VIEW_USER perm

When the staff accessing holdings in the holdings editor do not have the
VIEW_USER permission at a level sufficient to display the creator/editor
of a set of items, display the ID of the user instead of attempting and
failing to display the username, which causes a page rendering error.

Signed-off-by: Bill Erickson <berickxx@gmail.com>
Signed-off-by: Mary Llewellyn <mllewell@biblio.org>
Signed-off-by: Michele Morgan <mmorgan@noblenet.org>