(Almost) move FOF_Sudo into custishacks

Still needs to be moved away from list/list.html.tmpl and Bugzilla::Config::Auth
Bugzilla::Config::* code style, move validation functions away from Common
Make user_info_class and user_verify_class values dynamic

(also allows to remove FOF_Sudo from Bugzilla::Config::Auth)
Move &fof_sudo= param away from list/list.html.tmpl