Refactoring, housekeeping, documentation

Add a class diagram. Still needs some details.
Refactor to better respect SOLID principles.
Housekeeping, move and rename classes/files.

app/include/pwm/PWMControlFacade.h

@@ -0,0 +1,18 @@
+#ifndef PWMCONTROLFACADE_H_
+#define PWMCONTROLFACADE_H_
+
+#include <filesystem>
+#include <memory>
+#include <regex>
+#include <vector>
+
+#include <pwm/PWMControl.h>
+
+#define HWMON_BASE_PATH "/sys/class/hwmon"
+
+class PWMControlFacade {
+public:
+  std::vector<std::shared_ptr<PWMControl>> PWMControls();
+};
+
+#endif // PWMCONTROLFACADE_H_