Bug 15166: Make output_pref takes a string in parameter

Bug 15166: Make output_pref takes a string in parameter

To simplify the management of dates, it would be great that output_pref takes a string in parameter.

  my $date = $input->param('my_date');
  $date = eval { dt_from_string( $date ) } if $date;
  $date = output_pref({dt => $date}) if $date;

Could be replace with:

  my $date = output_pref({ str => $input->param('my_date') });

Tested with t/DateUtils.t, passed OK.
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>