chuni/chusan: added LED output to DLLs (will break most DLLs)

Credits: somewhatlurker, skogaby
https://dev.s-ul.net/skogaby/segatools/-/blob/ongeki-15093/

chuniio/ledoutput.h

@@ -0,0 +1,19 @@
+/*
+    LED output functions
+    
+    Credits:
+    somewhatlurker, skogaby
+*/
+
+#pragma once
+
+#include <windows.h>
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "chuniio/config.h"
+
+extern HANDLE led_init_mutex;
+int led_output_init(struct chuni_io_config* const cfg);
+void led_output_update(uint8_t board, const byte* rgb);