Bug 29897: Display author's identifiers

Bug 29897: Display author's identifiers

This new enhancement add the capability to list the different
identifiers of authors. It is helpful for research publications for
instance.

This patch will add a new "Author identifiers" tab on the detail page
(OPAC) of a bibliographic record, with the list of the authors and their
identifiers.
On the detail page of the authority record, the same identifier list
will be displayed.

Test plan:
Create some authority with
024
  $a source
  $2 number
  $6 link to the source
With the pref turned ON you will be able to see the new information.

Sponsored-by: Orex Digital
Signed-off-by: Orex Digital <info@orex.es>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>