Expansion: variable substitution V1 attempt

Norm has been checked, test are not up to date. Wildcard management and
filename expansions still to be done.

tests/expansion.c

@@ -6,7 +6,7 @@
 /*   By: jguelen <jguelen@student.42.fr>            +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2025/02/23 15:00:18 by jguelen           #+#    #+#             */
-/*   Updated: 2025/02/28 14:23:30 by jguelen          ###   ########.fr       */
+/*   Updated: 2025/03/01 11:07:17 by jguelen          ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
@@ -43,6 +43,7 @@ static void test_insert_instr(void)
 	free(line);
 }
 
+//Test to be remade since structures changed in the function calls and returns.
 static void	test_env_variable_expansion(void)
 {
 	char	*token;