feat: finish string helper.

- finish Split() in string helper.
- make complement to testbench test code.

src/ParserHelper.hpp

@@ -6,7 +6,5 @@ namespace YYCC::ParserHelper {
 
 	bool Parse(const std::string& strl, int& ret, int base = 10);
 	int Parse(const std::string& strl, int base = 10);
-	bool ToString(int val, std::string& ret, int base = 10);
-	std::string ToString(int val, int base = 10);
 
 }