[web/request] Restore attribute setting for search_state
This was dropped in 1f84295bfe95 when `search_state` attribute was turned into
a property, but without a setter. So adding a setter here restoring previous
behaviour, as some tests and cubes use it.
Related to #4875761.
[MESSAGES CONTROL]
disable-msg = C0301
[VARIABLES]
# Enable / disable this checker
enable-variables = yes
additional-builtins = _, display_name
[BASIC]
required-attributes=
attr-rgx = (w|[a-z_][a-z0-9_]{2,30})
variable-rgx = (w|[a-z_][a-z0-9_]{2,30})$
argument-rgx = (w|[a-z_][a-z0-9_]{2,30})$
[TYPECHECK]
generated-members=debug,info,notice,warning,error,critical,exception