Add mapping logic and serialization for writing

app/include/fan/HwmonFan.h

@@ -1,6 +1,7 @@
 #ifndef HWMONFAN_H_
 #define HWMONFAN_H_
 
+#include <boost/json/object.hpp>
 #include <memory>
 
 #include <fan/Fan.h>
@@ -15,6 +16,8 @@ public:
   void pwm(int percent) override;
   int rpm() override;
 
+  json toJson() const override;
+
 private:
   std::shared_ptr<PwmControl> mPwmControl;
   std::shared_ptr<Sensor> mRpmSensor;