Bug 35540: Separate StaffListsHome block from the table block

Bug 35540: Separate StaffListsHome block from the table block

This patch makes some minor changes to template markup and CSS so that
"page-section" divs have consistent margins.

To test, apply the patch and rebuild the staff interface CSS.

- Go to Tools -> HTML customizations and create a new entry in
  StaffListsHome, StaffPatronsHome, and StaffPOSHome regions.
- Confirm that those customizations are displayed well on each of those
  corresponding pages: The lists home page, the patrons home page, and
  the Point of Sale home page.
- Confirm that other pages affected by the CSS change still display
  correctly. These pages have an added bottom margin on the main
  "container" of content. For example:
  - Patrons -> Patron search results
  - Catalog -> Catalog search results (especially results with multiple
    pages)
  - Circulation -> Circulation history
  - Reports -> Saved SQL reports

Signed-off-by: Caroline Cyr La Rose <caroline.cyr-la-rose@inlibro.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>