Bug 25427: Make authority subfield management interface consistent MARC view

Bug 25427: Make authority subfield management interface consistent MARC view

This patch makes a couple of minor changes to the authority MARC
subfield structure administration interface to make it more consistent
with the corresponding MARC subfield interface.

To test, apply the patch and go to Administration -> Authority types.

- Pick an authority type to edit, for instance PERSO_NAME, and choose
  'MARC structure' from the Actions menu.
- Pick a tag to edit and select "Subfields" from the Actions menu.
- In the table of subfields for that tag, each subfield in the first
  column should link to the edit interface for that subfield (its tab
  pre-selected).
- The "Edit" button in that table should do the same.

Signed-off-by: Heather Hernandez <heather_hernandez@nps.gov>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>