Bug 23414: Use Koha Item objects in buildKohaItemsNamespace

Bug 23414: Use Koha Item objects in buildKohaItemsNamespace

Removing the use of C4::GetItemsInfo cuts down on the number of DB requests and speeds things up

To test I added 100 items to each of the first 20 records returned by a search for 'a'
I saw a reduction from ~30 seconds to ~26 seconds

This also makes the code a little cleaner and moves us toward the Koha namespace

To test:
1 - Perform a search in the OPAC and STaff Client with the Browser Console opened (F12)
2 - View the netwrok tab and see how long the pages take to load
3 - Apply the patches, restart all the things
4 - Repeat and note if the results are returned faster

Signed-off-by: Liz Rea <wizzyrea@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>