refactor: refactor old IOHelper.

- move pointer left padding macro into single header file.
- move utf8 fopen into single header but not finished.
- add testbench for pointer left padding macro.
- add system pointer size detector according to new migrated features requested.

testbench/CMakeLists.txt

@@ -8,6 +8,7 @@ PRIVATE
     yycc/flag_enum.cpp
     yycc/constraint.cpp
     yycc/constraint/builder.cpp
+    yycc/patch/ptr_pad.cpp
     yycc/string/op.cpp
     yycc/string/reinterpret.cpp
     yycc/num/parse.cpp