Bug 31799: Add REST endpoint to modify a biblio's item

Bug 31799: Add REST endpoint to modify a biblio's item

To test:
1. Apply patch
2. Set RESTBasicAuth preference to true
3. Get a biblio with an item
4. Make a PUT request to /api/v1/biblios/:biblio_id/items/:item_id with a json body that represents an item to replace
5. Check that the item was modified
6. Sign off

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>