Monitor for Lithium battery cells

[ffenix113]

Discussed in #22

^{Originally posted by Hedda February 2, 2024}
https://github.com/osaether/nrf_cell_mon

[Hedda]

While not sure if this "as-is" code is open source the Zigbee battery monitor concepts described here might still be useful:

https://github.com/SiliconLabs/zigbee_applications/tree/master/zigbee_battery_monitor

[ffenix113]

I just merged ADC implementation with battery power and soil moisture ADC sensors, and I think this should be now supported, if configured correctly. When I will update the docs to showcase new sensor configurations - this could be easier to test.

I will try this out when I would have ability and option to do so, or if anybody else would do this before I would have time for it - also great!