Bug 18433: Remember item search results selected rows in session storage

Bug 18433: Remember item search results selected rows in session storage

Session storage is not shared between browser tabs, and is cleared when
a tab is closed, so it seems like a good fit for storing selected rows

Test plan:
1. Go to item search (intranet) and submit the form
2. Select some rows on the first page by clicking on checkboxes
3. Go to another page of results
4. Select more rows
5. Go back to the first page
6. Selected rows should still be checked
7. Play with sorting and filtering, and see that selected rows are
   always checked
8. Export as CSV and as a barcodes file, verify that the export contains
   all selected rows
9. Click on 'Clear selection', it should deselect all rows from all
   pages
10. Select some rows again
11. Click on 'Edit search' and submit the same search
12. No row should be selected
13. Select some rows again
14. Refresh the page and submit again the same search
15. No row should be selected

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>