Bug 23823: Allow system preferences to be bookmarked

Bug 23823: Allow system preferences to be bookmarked

Test plan:
1) Log in to Staff UI with superlibrarian permissions
2) Go to System Preferences /cgi-bin/koha/admin/preferences.pl
3) Next to each preference, there should now be a bookmark icon
4) The bookmark icon links to a search for the exact preference name
5) The link can be bookmarked for quick reference to the specific
preference

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Séverine QUEUNE <severine.queune@bulac.fr>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>