Add battery info

[pauldeng]

Hi repo owner,

Appreciate your hard work.

Would be great if battery info can be added into the payload, so I do not need to guess if it is battery dead or no cellular coverage.

The new payload could be like this:

{
  "Timestamp": 1692091468,
  "Battery": {
    "Percentage": 85,
    "Voltage": 3.7
  },
  "Location": {
    "Altitude": 123.456,
    "Latitude": 234.567,
    "Longitude": 345.678,
    "Accuracy": 1.2,
    "Speed": 23.4,
    "UnixTimeStamp": 1692091468
  },
  "CellQuality": {
    "RSRP": "-97",
    "RSRQ": "-12",
    "RSSI": "-63",
    "SNR": "0"
  },
  "CellInfo": {
    "RxQual": "3",
    "CellID": "192",
    "EARFCN": "9410",
    "PLMN": "50501",
    "Operator": "Telstra Mobile"
  }
}

Cheers,
Paul

[philwareublox]

This would take a little longer to implement as the XPLR device uses the bq27520 device, and not the bq274xx device which Zephyr already has a simple driver for.

Of course, the XPLR-IoT-1-Software repo has the driver for it, which I could re-use.