Bug 25503: Add option to export items bundle contents in checkouts table

Bug 25503: Add option to export items bundle contents in checkouts table

Test plan:
1. Enable system preference ExportCircHistory
2. Create an item bundle (see bug 28854 comment 458)
3. Check out the item bundle
4. In the checkouts table, check the box in column "Export",
   choose export format 'MARC with items', check "Export items bundle
   contents" and click on "Export" button
   The exported file should contain the biblio and item created at step
   2, but also the biblio and items that are part of the bundle

Signed-off-by: Marie-Luce <marie-luce.laflamme@inlibro.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Marie-Luce <marie-luce.laflamme@inlibro.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
https://bugs.koha-community.org/show_bug.cgi?id=25508
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>