Zniffer: Add new commands for selecting LR channels

[AlCalzone]

The latest Zniffer firmware allows selecting LR channels (Classic + A, Classic + B, A + B). We should add support for that.

[hceuterpe]

Any chance this would expose channel 3 background RSSI value in HA? Currently I noticed that only 0, 1, 2 background RSSI values get polled with my controller.

[AlCalzone]

Zniffer is unrelated to your issue. Channel 3 is Z-Wave Long Range and only "exists" when your controller is set to an LR capable region.

[hceuterpe]

Weird. It's definitely set to US LR since 67 of my 93 devices are currently included via LR.
The background RSSI channel 3 value shows up in Z-Wave JS logs, but HA for some reason doesn't even pick it up (just 0-2)...

[kpine]

The background RSSI sensors are statically defined, not discovered.

If you are looking to contribute a PR, this would be an easy one. However, it does possibly present a complication: without a way to discover the number of supported channels, simply adding a 4th channel will result in a non-functional entity for non-LR regions. Whether the HA core devs care about that, I can't say. Alternatively, the linked code would need to be re-written to dynamically add the sensors as the statistics are received, but this may result in unavailable entities until stats are received (not sure).