[Feature Request]: low-power states for TRACKER/SENSOR roles

[andrekir]

Platform

NRF52, ESP32

Description

SENSOR and TRACKER roles can benefit from exponential increase in battery life by primarily remaining in low-power states (including LoRa radio off) and only waking up during scheduled broadcast intervals.

Since the ESP32 library already provides sleep methods, it looks like a good starting point to explore "what and where" these low-power states can be triggered and how they fit in the existing power Finite State Machine (FSM) design.

Then this foundation can be streamlined to the other architectures by implementing their own low-power/sleep methods (Related info exploring NRF52 sleep in #2822).

This feature request is a work in progress. Input, feedback, and suggestions are welcome.