Bug 15685: Allow creation of items (AcqCreateItem) to be customizable per-basket

Bug 15685: Allow creation of items (AcqCreateItem) to be customizable per-basket

This adds a new basket attribute (create_items) that can optionally be
set to override AcqCreateItem.

The following have been modified to reflect this (with the value of
create_items that causes them to behave differently in parentheses):
  * Cancelling receipt of an order (receiving)
  * Creating an order by hand or from MARC (ordering)
  * Receiving an order (receiving)
  * Showing orders with uncertain price (ordering)
  * Showing orders (receiving)
  * Showing acquisition details in the OPAC (ordering)

Test plan:
  1) Create baskets with "Create items when:" set to ordering,
     receiving, cataloging and unset.
  2) Test each of the above for each of these baskets, verifying that
     the basket-specific attribute overrides AcqCreateItem if set and
     falls back to the syspref otherwise.

NOTE: A check of AcqCreateItem in opac-detail.tt was removed because it
was redundant; the code path in question cannot be triggered unless
create_items/AcqCreateItems is set to the correct value anyway.

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Barbara Fondren <bfondren@roundrocktexas.gov>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>