Bug 23924: Add --date-field to add_date_fields_to_marc_records.pl

Bug 23924: Add --date-field to add_date_fields_to_marc_records.pl

The date used in the script will use this parameter, instead of today.

Test plan:
Use the POD of the script to understand how this flag works. Then use
the script to create fields with a date contained in a specific MARC
field.

Signed-off-by: Hugo Agud <hagud@orex.es>
Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>