Bug 31220: Pass label batch and ids to label-create-pdf

Bug 31220: Pass label batch and ids to label-create-pdf

This patch fixes a malformed link to print selected labels
and fix error:
Can't locate object method "get_attr" via package "-2" (perhaps you forgot to load "-2"?) at /usr/share/koha/intranet/cgi-bin/labels/label-create-pdf.pl line 126.

To test:
1 - Create a new label batch with some items
2 - Select 1 or more
3 - Export selected labels
4 - Download as PDF
5 - It works!

Signed-off-by: Sally <sally.healey@cheshiresharedservices.gov.uk>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>