Bug 31798: Add REST endpoint to add a biblio's item

Bug 31798: Add REST endpoint to add a biblio's item

To test:
1. Apply patch
2. Set RESTBasicAuth preference to true
3. Get a biblio
4. Make a POST request to /api/v1/biblios/:biblio_id/items with a json body that represents the new item
5. Check that the item is created
6. Sign off

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>