Bug 31115: Add additional_attributes support to GetInvoices

Bug 31115: Add additional_attributes support to GetInvoices

This patch adds support for searching additional_fields when retrieving
invoices using C4::Acquisition::Invoices.

To test:
1. Apply this patch
2. Run:
   $ kshell
  k$ prove t/db_dependent/Acquisition.t
=> SUCCESS: Tests pass!
3. Sign off :-D

Sponsored-by: The Research University in the Helmholtz Association (KIT)
Signed-off-by: Michaela Sieber <michaela.sieber@kit.edu>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>