switch mouse button constants to those defined in the HID library.

This is a leakage from the KeyboardioHID library

src/MouseKeyDefs.h

@@ -3,9 +3,9 @@
 #define IS_MOUSE_KEY             B00010000
 
 // Synthetic, not internal
-#define KEY_MOUSE_BTN_L 0x01  // Synthetic key
-#define KEY_MOUSE_BTN_M 0x02  // Synthetic key
-#define KEY_MOUSE_BTN_R 0x03  // Synthetic key
+#define KEY_MOUSE_BTN_L MOUSE_LEFT // Synthetic key
+#define KEY_MOUSE_BTN_M MOUSE_MIDDLE  // Synthetic key
+#define KEY_MOUSE_BTN_R MOUSE_RIGHT  // Synthetic key
 
 
 #define KEY_MOUSE_UP            B0000001