Bug 26134: (bug 23463 follow-up) Fix add to basket from staged file

Bug 26134: (bug 23463 follow-up) Fix add to basket from staged file

There is a ->store call missing when we attempt to create a new item.

Test plan:
- set at least one value in MARCItemFieldsToOrder
- add to a basket via staged file with at least one value matching your MARCItemFields mappings
- set required fields for your order and click Save
=> Without this patch you got:
receive error: "DBIx::Class::Storage::DBI::_dbh_execute(): Column 'itemnumber' cannot be null at /kohadevbox/koha/Koha/Acquisition/Order.pm line 113
 at /usr/share/perl5/DBIx/Class/Exception.pm line 77"
=> With this patch applied the order has been created successfully

Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>