Bug 35489: Add a hidden input for itemnumber even if item has no barcode

Bug 35489: Add a hidden input for itemnumber even if item has no barcode

This page is a single form, all fields must have inputs to avoid data loss/mismatch

To test:
1 - Find a record in the catalog and add or edit items to have one item with a barcode and one without
2 - Place an item level hold on the item with no barcode
3 - Place another hold for a different patron on the item with a barcode
4 - From the holds table add an expiration date to the hold with a barcode and save
5 - Note the hold on the item with no barcode is now on the item with a barcode and the other hold is now a next available hold
6 - Delete the holds
7 - Apply patch
8 - Repeat 2-4
9 - Confirm the itemnumbers for the holds have not changed

Signed-off-by: Andrew Fuerste-Henry <andrewfh@dubcolib.org>
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>