fix(station-g3): expose FEM gain preferences

variants/station_g3_esp32/LoRaFEMControl.h

@@ -0,0 +1,20 @@
+#pragma once
+
+class LoRaFEMControl {
+public:
+  void init();
+  void setSleepModeEnable();
+  void setTxModeEnable();
+  void setRxModeEnable();
+  void setLNAEnable(bool enabled);
+  void setPAGainEnable(bool enabled);
+
+  bool canControlLNA() const;
+  bool canControlPAGain() const;
+  bool isLNAEnabled() const { return lna_enabled; }
+  bool isPAGainEnabled() const { return pa_gain_enabled; }
+
+private:
+  bool lna_enabled = true;
+  bool pa_gain_enabled = false;
+};