Bug 12906: Show shipment date in invoice search result list

Bug 12906: Show shipment date in invoice search result list

Patch adds the shipment as a new separate column to the
search results of the invoices search.

To test:
- Search for invoices in the acquisition module
- Verify the results table shows the shipment date
- Verify that sorting works correctly

Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>