Bug 30426: Add missing C4::Auth and C4::Output imports

Bug 30426: Add missing C4::Auth and C4::Output imports

This patch adds missing function imports for C4::Auth and C4::Output
in the opac/svc/suggestion script.

Test plan:

1. Go to http://localhost:8081/cgi-bin/koha/admin/didyoumean.pl
2. Turn on some plugins
3. Go to http://localhost:8080/cgi-bin/koha/opac-search.pl?idx=&q=test&weight_search=1
4. Note in your browser's Network tab that the call to
   http://localhost:8080/cgi-bin/koha/svc/suggestion?render=stub&q=test
   generates a 200 response instead of a 500 error

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>