[web/session] make sure not to modify an inner value of session.data (closes #11217958) When we modify a mutable value stored in the session's data (dict-like object) we prevent an alternative session data handler (eg. pyramid-redis-session) from detecting this update and synchronizing it in its backend (like redis).

option_group_changed('port', 'main', 'web')
option_group_changed('query-log-file', 'main', 'web')
option_group_changed('profile', 'main', 'web')
option_group_changed('max-post-length', 'main', 'web')