Bug 32921: Honor SelfCheckTimeout when modal is open

Bug 32921: Honor SelfCheckTimeout when modal is open

To test:
1. Set the 'SelfCheckTimeout' system preference to something low for testing.
2. Make sure 'SelfCheckReceiptPrompt' is set to 'Show'.
3. Log in to SCO and press finish but leave the modal open.
4. Wait until the 'SelfCheckTimeout' time has expired, nothing happens.
5. Apply patch and try again. You should be logged out when SelfCheckTimeout expires.

Signed-off-by: Marius Mandrescu <marius.mandrescu@inLibro.com>
JD amended patch - fix indentation

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit e074ffa6be15c97e6724041b12d930ed70855f1d)
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>