Bug 24157: New permission - delete_invoices

Bug 24157: New permission - delete_invoices

Add a new permission to delete invoices

Test plan:
- Remove the new permission "delete_invoices" for a given patron,
use it to log in into Koha
- Create an invoice, try to delete it
=> There is no way to delete it
- Add the permission
=> Now you can delete the invoice

Sponsored-by: Galway-Mayo Institute of Technology
Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Alex Arnaud <alex.arnaud@biblibre.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>