Bug 18422 - Add Select2 to authority editor

Bug 18422 - Add Select2 to authority editor

Overview:
Repeat tag fails if authority field has select subfield (for example, UNIMARC 700$8, 800$a)
This patch adds Select2 to authority editor

Steps to Reproduce:
In authority editor repeat field that has select subfield

Actual Results:
Field does not repeat (copy is not created).
Console shows a js TypeError in cataloging.js: «$(...).select2 is not a function»

Expected Results:
Field will repeat (copy is created)

Additional Information:
Error happens in version 16.11+ after adding Select2 js functions. The easiest way to fix is to add Select2 to authority editor

Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>