feat: add ft_memcpy function

libft.h

@@ -61,4 +61,14 @@ void	*ft_memset(void *b, int c, size_t len);
 */
 void	ft_bzero(void *s, size_t n);
 
+/*
+	The memcpy() function copies n bytes 
+	from memory area src to memory area dst.  
+	If dst and src overlap, behavior is 
+	undefined.  Applications in which dst and 
+	src might overlap should use memmove(3) 
+	instead.
+*/
+void	*ft_memcpy(void *dst, const void *src, size_t n);
+
 #endif