AP_HAL: add power status bits to logger metadata

libraries/AP_HAL/AnalogIn.h

@@ -42,6 +42,16 @@ public:
     // failures can still be diagnosed
     virtual uint16_t accumulated_power_status_flags(void) const { return 0; }
 
+    // this enum class is 1:1 with MAVLink's MAV_POWER_STATUS enumeration!
+    enum class PowerStatusFlag : uint16_t {
+        BRICK_VALID = 1,                  // main brick power supply valid
+        SERVO_VALID = 2,                  // main servo power supply valid for FMU
+        USB_CONNECTED = 4,                // USB power is connected
+        PERIPH_OVERCURRENT = 8,           // peripheral supply is in over-current state
+        PERIPH_HIPOWER_OVERCURRENT = 16,  // hi-power peripheral supply is in over-current state
+        CHANGED = 32,                     // Power status has changed since boot
+    };
+
 #if HAL_WITH_MCU_MONITORING
     virtual float mcu_temperature(void) { return 0; }
     virtual float mcu_voltage(void) { return 0; }