Bug 37536: Update conditional to check for 'cud-saveitem'

Bug 37536: Update conditional to check for 'cud-saveitem'

In additem.pl and additem.tt all instances of 'saveitem' have been updated to 'cud-saveitem'
The javascript needs to be updated in the same way.

Test plan:
- Make sure acqcreateitem is set to "when placing an order"
- Create a basket with some orders
- Close the basket
- Go to your vendor and receive an order
- On the receive page, try to edit your item
=> Without the patch, the pop up page will open and then close, not allowing the item to be edited.
=> With this patch applied you will see the item edit form. Save and
confirm that the parent window is updated with the new value (actually
it's refreshed)

QA notes:
1. git grep 'saveitem'
2. Notice all instances in additem.pl and additem.tt have been updated to 'cud-saveitem'
3. Notice cataloging_additem.js checks if op != 'saveitem'
4. Check the files and verify the change makes sense

Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Emily Lamancusa <emily.lamancusa@montgomerycountymd.gov>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>