public void add_cookie_full (owned Cookie cookie, URI? uri, URI? first_party)
cookie to this, emitting the 'changed' signal if we are modifying an existing cookie or
adding a valid new cookie ('valid' means that the cookie's expire date is not in the past).
first_party will be used to reject cookies coming from third party resources in case such a security policy is set in the
uri will be used to reject setting or overwriting secure cookies from insecure origins.
null is treated as secure.
cookie will be 'stolen' by the jar, so don't free it afterwards.
the URI setting the cookie
the URI for the main document