Refactor files based on beta debug build (#645)

* Rename LegoUnkSaveDataWriter -> LegoCharacterManager

* Refactor mxomni into mxomni/mxmisc

* Refactor legoomni into legoomni/misc

* Resolve deps

* Refactor atom

* Refactor mxutil

* Refactor mxio

* Rename/relocate files

* Fix format

LEGO1/omni/include/mxio.h

@@ -0,0 +1,32 @@
+#ifndef MXIO_H
+#define MXIO_H
+
+#include "mxtypes.h"
+
+// mmsystem.h requires inclusion of windows.h before
+// clang-format off
+#include <windows.h>
+#include <mmsystem.h>
+// clang-format on
+
+// SIZE 0x48
+class MXIOINFO {
+public:
+	MXIOINFO();
+	~MXIOINFO();
+
+	MxU16 Open(const char*, MxULong);
+	MxU16 Close(MxLong);
+	MxLong Read(void*, MxLong);
+	MxLong Seek(MxLong, MxLong);
+	MxU16 SetBuffer(char*, MxLong, MxLong);
+	MxU16 Flush(MxU16);
+	MxU16 Advance(MxU16);
+	MxU16 Descend(MMCKINFO*, const MMCKINFO*, MxU16);
+
+	// NOTE: In MXIOINFO, the `hmmio` member of MMIOINFO is used like
+	// an HFILE (int) instead of an HMMIO (WORD).
+	MMIOINFO m_info;
+};
+
+#endif // MXIO_H