Bug 28554: In itemsearch sort item types filter by description

Bug 28554: In itemsearch sort item types filter by description

In itemsearch form, the item types filter should be sorted by description.

Test plan :
1) Create several values and descriptions in item types
2) Go to itemsearch
3) See filter by item types sorts on description and not on value

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>