[FL-2797] Signal Generator app (#1793)

* Signal Generator app
* MCO pin initialization in app
* furi_hal_pwm documentation

Co-authored-by: あく <alleteam@gmail.com>

applications/plugins/signal_generator/scenes/signal_gen_scene.c

@@ -0,0 +1,30 @@
+#include "../signal_gen_app_i.h"
+
+// Generate scene on_enter handlers array
+#define ADD_SCENE(prefix, name, id) prefix##_scene_##name##_on_enter,
+void (*const signal_gen_scene_on_enter_handlers[])(void*) = {
+#include "signal_gen_scene_config.h"
+};
+#undef ADD_SCENE
+
+// Generate scene on_event handlers array
+#define ADD_SCENE(prefix, name, id) prefix##_scene_##name##_on_event,
+bool (*const signal_gen_scene_on_event_handlers[])(void* context, SceneManagerEvent event) = {
+#include "signal_gen_scene_config.h"
+};
+#undef ADD_SCENE
+
+// Generate scene on_exit handlers array
+#define ADD_SCENE(prefix, name, id) prefix##_scene_##name##_on_exit,
+void (*const signal_gen_scene_on_exit_handlers[])(void* context) = {
+#include "signal_gen_scene_config.h"
+};
+#undef ADD_SCENE
+
+// Initialize scene handlers configuration structure
+const SceneManagerHandlers signal_gen_scene_handlers = {
+    .on_enter_handlers = signal_gen_scene_on_enter_handlers,
+    .on_event_handlers = signal_gen_scene_on_event_handlers,
+    .on_exit_handlers = signal_gen_scene_on_exit_handlers,
+    .scene_num = SignalGenSceneNum,
+};