Bug 16748: Add the ability to define due date in batch checkout

Bug 16748: Add the ability to define due date in batch checkout

This patch allows the librarian to pick the due date when batch checkout

Test plan:
Batch checkout using a hard due date
=> Notice that the due date is taken into account
Batch checkout the same barcodes with a different due date, to trigger the confirmation step
=> Notice that the due date is taken into account for the renewals

Signed-off-by: Henry Bolshaw <bolshawh@parliament.uk>

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>