App accessor: init (#433)

applications/accessor/accessor-event.h

@@ -0,0 +1,19 @@
+#pragma once
+#include <stdint.h>
+
+class AccessorEvent {
+public:
+    // events enum
+    enum class Type : uint8_t {
+        Tick,
+        Back,
+    };
+
+    // payload
+    union {
+        uint32_t menu_index;
+    } payload;
+
+    // event type
+    Type type;
+};