Add support for Smart motion notification using MQTT

[skynet01]

I have multiple camera brands Reolink, Amcrest even Wyze and pipe RTSP/RTMP/ONVIF from them into Scrypted and Home Assistant. If this proxy supported MQTT I could then pass smart motion events from one of those apps to Unifi Protect. This would make this unifi-proxy compatible with pretty much anything... it seems that maybe this is already setup since Frigate uses MQTT to pass the events... so maybe very little work is needed

Thanks so much for your consideration :)