mu3hook: Add initial Ongeki hook

mu3hook/config.h

@@ -0,0 +1,16 @@
+#pragma once
+
+#include <stddef.h>
+
+#include "board/config.h"
+
+#include "platform/config.h"
+
+struct mu3_hook_config {
+    struct alls_config alls;
+    struct aime_config aime;
+};
+
+void mu3_hook_config_load(
+        struct mu3_hook_config *cfg,
+        const wchar_t *filename);