Bug 19915: Use cn_sort values for getting inventory items

Bug 19915: Use cn_sort values for getting inventory items

To test:
1 - Catalog an item under LCC with callnumber GT95
2 - cn_sort should calculate as GT0095
3 - Go to inventory tool
4 - Enter a range that should have your item e.g LC GT90 to GT100
5 - Item is not returned
6 - Apply patch
7 - Item should be returned
8 - Verify things otherwise work as expected

Signed-off-by: Anne-Claire Bernaudin <anne-claire.bernaudin@univ-rennes1.fr>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
https://bugs.koha-community.org/show_bug.cgi?id=19905

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>