Added default temperature from ESP32 MCU and NRF52 MCU

Added NRF52Board.h and NRF52Board.cpp
Modified NRF52 variants to extend from NRF52Board to share common feature

src/helpers/ESP32Board.h

@@ -42,6 +42,11 @@ public:
   #endif
   }
 
+  // Temperature from ESP32 MCU
+  float getMCUTemperature() override {
+    return temperatureRead();
+  }
+
   uint8_t getStartupReason() const override { return startup_reason; }
 
 #if defined(P_LORA_TX_LED)