New feature: SONOFF SNZB-02 support for the legacy (imperative) branch

[Vadim Tkachenko]

Hello lurkers,

Alas, it so happened that I needed that, so it got added.

Here's how to configure it: https://github.com/home-climate-control/dz/wiki/HOWTO:-Zigbee-Sensors

Here's the sensors I'm using: https://www.amazon.com/gp/product/B08YJBMMC1/ (6 in use, 2 more in the mail)

Here's the hubs: https://www.amazon.com/gp/product/B09KXTCMSC and https://www.amazon.com/gp/product/B0B6P22YJC (one of them is declared as having limited feature set on Zigbee2MQTT page, but so far I haven't hit any limitations)

Beware, sensors will need to have their reporting for Temperature / measuredValue set to at least 1/60/5 so that measurement granularity yields acceptable control quality. They live for many months with that setting; I'm setting new sensors to 1/30/1 to test battery life. Batteries are cheap, too.

You will probably also want to set Settings (specific) / temperature_precision to 3.

Enjoy.

--vt

PS: Need other Zigbee sensors? Drop a note, adding them will be simple, all the framework is in place.