Bug 31665: Set today date for date cataloguing plugin

dateaccessioned.pl must pick today's date when the input gets the focus
on.

Test plan:
Edit an item, or create a new one.
Confirm that today's date is prefilled into the date's input when it's
empty and that it gets the focus on

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Michael Adamyk <madamyk@ckls.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit 140493faf7)
Signed-off-by: Jacob O'Mara <jacob.omara@ptfs-europe.com>

cataloguing/value_builder/dateaccessioned.pl

@@ -21,24 +21,21 @@
 # along with Koha; if not, see <http://www.gnu.org/licenses>.
 
 use Modern::Perl;
-use Koha::DateUtils qw( flatpickr_date_format );
-
 my $builder = sub {
     my ( $params ) = @_;
     my $function_name = $params->{id};
 
-    my $dateformat = flatpickr_date_format();
-
     my $res  = <<END_OF_JS;
 <script>
 /* from: cataloguing/value_builder/dateaccessioned.pl */
 
 \$(document).ready(function(){
     \$("#$function_name").flatpickr({
-        altInput: true,
-        altFormat: "$dateformat",
-        altInputClass: "input_marceditor flatpickr-input",
-        dateFormat: "Y-m-d"
+        onOpen: function(selectedDates, dateStr, instance) {
+            if (dateStr == '') {
+                instance.setDate(new Date());
+            }
+        }
     });
 });