[MEDIUM] cookie: support client cookies with some contents appended to their value

[MEDIUM] cookie: support client cookies with some contents appended to their value

In all cookie persistence modes but prefix, we now support cookies whose
value is suffixed with some contents after a vertical bar ('|'). This will
be used to pass an optional expiration date. So as of now we only consider
the part of the cookie value which is used before the vertical bar.
(cherry picked from commit a4486bf4e5b03b5a980d03fef799f6407b2c992d)