[Spring Boot] 비밀번호 암호화

- MemverService 

    @Transactional
    public Enum<? extends IResult> register(UserEntity user, EmailAuthEntity emailAuth) throws NoSuchAlgorithmException {
        EmailAuthEntity existingStudy = this.memberMapper.selectEmailAuthByEmailCodeSalt(
                emailAuth.getEmail(),
                emailAuth.getCode(),
                emailAuth.getSalt());
        
        StringBuilder authPasswordBuilder = new StringBuilder();
        MessageDigest ps = MessageDigest.getInstance("SHA-512");
        ps.update(user.getPassword().getBytes(StandardCharsets.UTF_8));
        for(byte hashByte : ps.digest()) {
            authPasswordBuilder.append(String.format("%02x", hashByte));
        }
        user.setPassword(authPasswordBuilder.toString());