Bug 35960: Use .val() instead of string concat to prevent potential XSS
Test plan:
1. Log out
2. Go to /cgi-bin/koha/mainpage.pl#somestring"with<html>char
3. Open the brower's inspector and find "auth_forwarded_hash" input
4. Make sure the value attribute is there and corresponds to the URL's
fragment. It should be URI-encoded.
Signed-off-by: Owen Leonard <oleonard@myacpl.org> Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net> Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>