[Keyboard] add treeadstone48 (#5405)

* Keyboard: add treeadstone48

* rename layout defines

* Use of pragma once

* move common include code

* fixed info.json

* change keymap layout from kc to normal

* fix alpha revision keymap

* fixed info.json

* remove USE_Link_Time_Optimization

keyboards/treadstone48/rev1/split_util.h

@@ -0,0 +1,16 @@
+#pragma once
+
+#include <stdbool.h>
+#include "eeconfig.h"
+
+#define SLAVE_I2C_ADDRESS           0x32
+
+extern volatile bool isLeftHand;
+
+// slave version of matix scan, defined in matrix.c
+void matrix_slave_scan(void);
+
+void split_keyboard_setup(void);
+bool has_usb(void);
+
+void matrix_master_OLED_init (void);