Decrypts an AES-256 encrypted file using the provided key and saves the decrypted content to another file.
aes256_decrypt_f({key}, {input_file}, {output_file})
Decrypt a file “encryptedFile.txt” using the key “mysecretkey” and save it as “decryptedFile.txt”
aes256_decrypt_f("mysecretkey", "encryptedFile.txt", "decryptedFile.txt"); // returns success/failure