Bug 32112: Move 'Delete selected items' to its own line

Bug 32112: Move 'Delete selected items' to its own line

This moves the checkbox and its label out of the action field set
which makes it appear above the bottons instead of in front of it.

To test:
* Go to any record
* Select items and send to item batch delete
* Verify checkbox appears in front of button
* Apply patch
* Verify the checkbox and the yellow 'delete selected items' button
  are now on separate lines

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>