B4R Library rsMQTTBroker an MQTT broker for esp32 and esp8266

it is a wrapper for sMQTTBroker from here : https://github.com/terrorsl/sMQTTBroker

this simple MQTT broker is working on esp32 and esp8266
- it can work without callback,
- it can work with 6 callbacks on NewClient, Subscribe, UnSubscribe, Publish, RemoveClient, and LostConnection : it can help at debugging on a small network, but it will have an impact on performances.
- Mqtt 3.1.1 / Qos 0, 1 supported