Suggestion: Qt6 Mqtt class "QMqttSubscription" add signals

enum ClientState {
    Disconnected = 0,
    Connecting,
    Connected
};
Q_ENUM(ClientState)

Q_SIGNALS:
    void connected();
    void disconnected();
    // ...
    void stateChanged(ClientState state);

enum SubscriptionState {
    Unsubscribed = 0,
    SubscriptionPending,
    Subscribed,
    UnsubscriptionPending,
    Error
};

Q_SIGNALS:
    void stateChanged(SubscriptionState state);