Bug 37014: Fix after-modal-POST to transmit "not_returned" message

Bug 37014: Fix after-modal-POST to transmit "not_returned" message

The bug report addresses an issue where the message "Item was not checked in" erroneously appears during the second POST after a manual or modal check-in process.

1. In circ/returns.pl:
   - Introduced a new hash `%rinot_returned` to track items not returned across pages.
   - Updated the logic to capture the "not returned" status from the query parameters.
   - Adjusted the input processing loop to include `not_returned` status.
   - Modified the section handling barcode check-ins to appropriately initialize and update the `not_returned` status.

2. returns.tt:
   - Added hidden input fields in the template to include `not_returned` status in the form submissions.

The changes ensure that the "not_returned" status is correctly tracked and displayed, preventing the erroneous message from appearing on subsequent POST requests.

1. Perform a manual check-in of an item, but make some warning modal appear: for ex., transfer: check-in the item in not home library.
2. Press OK on the modal. There will be a POST transition again to redraw the checked-in items list.
3. Verify that the "Item was not checked in" message appears erroneously near the item's row.
4. Apply the patch.
5. Repeat steps 1-3 and check that there will be no erroneous "Item was not checked in" message.

Signed-off-by: Tadeusz „tadzik” Sośnierz <tadeusz@sosnierz.com>
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>