allow others passwords encryption algos

[lianglee]

allow others passwords encryption algos,
bcrypt, argon2i, md5, from v5.1 default is set to bcrypt

you can change to any one by adding a new hook into your component

ossn_add_hook('user', 'password:algorithm', 'change_password_algo');
function change_password_algo(){
        return 'argon2i';
}