Bug 16427: Add direct link to authority records from staff detail view (MARC21 subjects)

Bug 16427: Add direct link to authority records from staff detail view (MARC21 subjects)

I added a magnigying glass icon in the staff detail view that links to
the authority records.

Test Plan:
1) On the Koha staff page, create a new authority. The type of authority
   will be: Topical Term.
2) When creating authority, in tab 1 under -HEADING--TOPICAL TERM enter
   the topical term or geographic name entry element and then save the
   new authority e.g. science.
3) In circulation, search the catalog for a random book. Click the title
   of the book and you will be taken to the book details.
4) Edit the record and in tab 6, scroll down the - SUBJECT ADDED
   ENTRY--TOPICAL TERM and repeat this tag (the icon next to the title).
5) Edit the Topical term or geographic name entry element by clicking
   the button on the right of the bar.
6) In the Search main heading ($a only) enter your topical term e.g.
   science.
7) Press search, and then in the table that pops up, click 'choose'.
8) Save your edits and the new topical term will be in the 'Subject(s)'
   list of the book details.
9) Notice that there is no magnifying glass icon.
10) Apply this patch
11) Notice that there is now a magnifying glass icon next to the topical
    term.
12) Click on the magnifying glass and it will take you directly to the
    authorities records

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>