Bug 29105: Add effective_itemtype handling to items api

Bug 29105: Add effective_itemtype handling to items api

This patch adds effective_item_type_id to the items api.

We overload the to_api method to append the effective_item_type_id field
with that of the effective itemtype code.

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit dc75b5d5cd181d8f8e50e98adb7afc69fc6a8838)

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
(cherry picked from commit f00a28b576ed9c2efcff22f43f2261f7d9b6ef12)
Signed-off-by: Arthur Suzuki <arthur.suzuki@biblibre.com>