[webrequest] Lazy-load search_state - The update_search_state function will hit the session data only if __mode is present in the form. - set_search_state keep the same semantics - Direct access to search_state in the session data is changed by an access to the new property. Closes #4875761

etc/init.d
etc/cubicweb.d
etc/bash_completion.d
usr/bin
usr/share/doc/cubicweb-ctl
var/log/cubicweb
var/lib/cubicweb/backup
var/lib/cubicweb/instances