Bug 27846: admin folder

Bug 27846: admin folder

Modified breadcrumbs to be accessible, in particular for a
screen-reader.

Made the block of breadcrumbs be a <nav aria label="Breadcrumb"
class="breadcrumb"> with an ordered list inside. The last breadcrumbs
also has aria-current="page" to specify that it is the current page.

To test:
1) Apply patch
2) Build scss file
3) Ensure each of the files in the admin folder has breadcrumbs that are
   in a <nav aria label="Breadcrumb" class="breadcrumb"> block
4) Ensure that there is an ordered list in the block of breadcrumbs
5) Ensure that the last breadcrumb has aria-current="page"
6) Ensure that the breadcrumbs on each page of the staff client
   belonging to these files look the same as before, but the '>' symbol
   is replaced with '/' and the last breadcrumb has bold text
7) Ensure that when the last breadcrumb is clicked it takes you to the
   page you are currently on

Sponsored-by: Catalyst IT
Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>