Bug 26704: Update Koha::Item to use Koha::Object::Messages

Bug 26704: Update Koha::Item to use Koha::Object::Messages

Use the newly introduced Koha::Object::Messages system to pass
additional information provided by object methods internally in the
objects themselves.

This patch updates the existing bespoke passing scheme to something
we've formally agreed to adopt going forward.

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>