Bug 28046: Add "Additional fields" link on acquisition navigation menu

Bug 28046: Add "Additional fields" link on acquisition navigation menu

This patch adds a link to the "Additional fields" page in Administration
to the sidebar menu shown on Acquisitions pages.

To test, apply the patch and go to Acquisitions.

- In the sidebar menu you should see a "Manage order basket fields"
  link.
- The link should take you directly to the "Additional fields for
  'aqbasket'" page.

Signed-off-by: Séverine QUEUNE <severine.queune@gmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>