How to configure auth.pgsql.password_hash for django password

I want emqx to authenticate my Django user. Django uses PBKDF2 with sha356 + 150000 iterations + salt. Django has a `make_password` method to hash plain password in a secure way.

```python
>>> from django.contrib.auth.hashers import make_password
>>> make_password("hello world")
'pbkdf2_sha256$150000$YSu4ev2bmi9t$YieK5QrYzdlktW9E1EymOjY3T0RUbF8EaPoR57otsq4='
```

it is in the following format:

```
$$$
```

Check this for more info: https://docs.djangoproject.com/en/3.0/topics/auth/passwords/#how-django-stores-passwords.

I can break the string into subsequent components and store them in separate columns.

How should I configure `auth.pgsql.password_hash` in this case??

I am thinking of something the following:

```
auth.pgsql.password_hash = salt,pbkdf2,sha256,150000,32
auth.pgsql.auth_query = select password from mqtt_user where username = '%u' limit 1
```

Will it work? Is the configuration correct? How will emqx know what the salt is? Or as of now using salt with pbkdf2 is not supported? Or should I store the salt with password hash in one column only with some separator(or without separator)? Also, should the hash and salt both be base64 encoded?