The reason code and MQTTv5 properties for PUBACK/PUBREC/PUBREL/PUBCOMP are not available to the client code

[eisaev]

For PUBACK, PUBCOMP, PUBREC the reason code and MQTTv5 properties are parsed, but not used in any way. For PUBREL the reason code and MQTTv5 properties are not even parsed. It would be good to have callbacks for these types of packets so that the client code can analyze the reason code and MQTTv5 properties. PUBACK and PUBCOMP already have on_publish callback, but it does not return the necessary data.

[MaSchaxx]

This issue seems to have been solved in #656, but unfortunately it has still not been merged for over half a year now. It would be very helpful to see some new activities under this project.