Bug 25826: Forbid changing the hidden attributes for biblionumber

Bug 25826: Forbid changing the hidden attributes for biblionumber

This patch tweaks the UI so it forbids changing the hidden values when
they are correct (i.e. when they are not hidden in OPAC and intranet).

To test:
1. Apply the first patch
2. Play with the hidden values of the subfield you have mapped to
   biblio.biblionumber in your picked framework. This is usually 999$c
   in MARC21, and 001 in UNIMARC.
=> SUCCESS: When you verify the about.pl, it mentions issues when you
hide in some of the interfaces
3. Apply this patch and reload everything
4. Repeat 2
=> SUCCESS: If your framework is 'ok', it prevents you from editing this
values, otherwise you can change them.

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>