ipsec-types: Restrict the use of %unique and other keywords when parsing marks

%unique (and the upcoming %same key) are usable in specific contexts only.
To restrict the user from using it in other places where it does not get the
expected results, reject such keywords unless explicitly allowed.

src/libcharon/plugins/kernel_netlink/kernel_netlink_net.c

@@ -2925,7 +2925,7 @@ static status_t manage_rule(private_kernel_netlink_net_t *this, int nlmsg_type,
 			msg->rtm_flags |= FIB_RULE_INVERT;
 			fwmark++;
 		}
-		if (mark_from_string(fwmark, &mark))
+		if (mark_from_string(fwmark, MARK_OP_NONE, &mark))
 		{
 			chunk = chunk_from_thing(mark.value);
 			netlink_add_attribute(hdr, FRA_FWMARK, chunk, sizeof(request));