INA3221 sensor: use for bus voltage & environment metrics (#4215)

* use INA3221 for bus voltage; fixes for telemetry variants

- add to sensors available for environment telemetry
  (to report voltage/current)
- add vars to define channels to use for battery voltage
  (for getBusVoltage) and environment metrics (default
  to CH1 for both)
- write to the correct fields on the measurement struct
  depending on the measurement variant, and DRY up the
  sensor measurement collection code a bit
- this might be suitable for a common implementation for
  the INA* sensors in a future PR...

* formatting

* derp

---------

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

src/modules/Telemetry/Sensor/INA3221Sensor.h

@@ -12,6 +12,21 @@ class INA3221Sensor : public TelemetrySensor, VoltageSensor
   private:
     INA3221 ina3221 = INA3221(INA3221_ADDR42_SDA);
 
+    // channel to report voltage/current for environment metrics
+    ina3221_ch_t ENV_CH = INA3221_CH1;
+
+    // channel to report battery voltage for device_battery_ina_address
+    ina3221_ch_t BAT_CH = INA3221_CH1;
+
+    // get a single measurement for a channel
+    struct _INA3221Measurement getMeasurement(ina3221_ch_t ch);
+
+    // get all measurements for all channels
+    struct _INA3221Measurements getMeasurements();
+
+    bool getEnvironmentMetrics(meshtastic_Telemetry *measurement);
+    bool getPowerMetrics(meshtastic_Telemetry *measurement);
+
   protected:
     void setup() override;
 
@@ -22,4 +37,14 @@ class INA3221Sensor : public TelemetrySensor, VoltageSensor
     virtual uint16_t getBusVoltageMv() override;
 };
 
+struct _INA3221Measurement {
+    float voltage;
+    float current;
+};
+
+struct _INA3221Measurements {
+    // INA3221 has 3 channels
+    struct _INA3221Measurement measurements[3];
+};
+
 #endif