Remove `dispatch_results` at inlane

[hujw77]

Since we remove on_message_delivered callback, dispatch_results have no meaning at lnlane.

    struct DeliveredMessages {
        // Nonce of the first message that has been delivered (inclusive).
        uint64 begin;
        // Nonce of the last message that has been delivered (inclusive).
        uint64 end;
        // Dispatch result (`false`/`true`), returned by the message dispatcher for every
        // message in the `[end; begin]` range.
        // The `MAX_UNCONFIRMED_MESSAGES` parameter must lesser than 256 for gas saving
        uint256 dispatch_results;
    }