Bug 36529: manage_additional_fields permission for more than acquisitions and serials

Bug 36529: manage_additional_fields permission for more than acquisitions and serials

This patch renames the manage_additional_fields permission to remove
the specificity of acquisitions orders and serial subscriptions.
Since each additional field requires a corresponding permission, I
wrote each of them next to it. It makes it very long, but right now
there isn't really a way to link permissions other than the permission
description.

To test:
1. Apply patch
2. Go to a patron account
3. Click More > Set permissions
4. Go to the Administration panel permissions and open the
   sub-permissions
5. Check that the manage_additional_fields permission description
   makes sense, check grammar and spelling, try the various
   combinations

Signed-off-by: Pedro Amorim <pedro.amorim@ptfs-europe.com>
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>