Hoist slider from board into chunihook

Diva slider uses the quasi-JVS framing used by all other SEGA
boards, the Chunithm slider is a special case.

board/slider-frame.h

@@ -1,25 +0,0 @@
-#pragma once
-
-#include <windows.h>
-
-#include <stddef.h>
-#include <stdint.h>
-
-#include "hook/iobuf.h"
-
-enum {
-    SLIDER_FRAME_SYNC = 0xFF,
-};
-
-struct slider_hdr {
-    uint8_t sync;
-    uint8_t cmd;
-    uint8_t nbytes;
-};
-
-HRESULT slider_frame_decode(struct iobuf *dest, struct iobuf *src);
-
-HRESULT slider_frame_encode(
-        struct iobuf *dest,
-        const void *ptr,
-        size_t nbytes);