auth tokens are deleted when using OpenStackConfig

it appears that https://review.opendev.org/c/openstack/openstacksdk/+/893283 has introduced a regression when using tokens with OpenStackConfig.
This simple script doesn't return the same output after this commit:

--
import openstack

config = openstack.config.OpenStackConfig(load_yaml_config=False,
            load_envvars=False).get_one_cloud(
    interface='publicURL',
    region_name='RegionOne',
    auth_type='token',
    auth={
        'project_id': '1234',
        'project_domain_id': None,
        'token': '1234',
        'auth_url': 'http://127.0.0.1/'
    })
print(config._auth._token)
--

In older openstacksdk releases, it displays the token passed in ['auth']['token']
On master, it displays 'None'.

When building the config it seems that magic_fixes() makes some incorrect changes:

1. If config['auth']['token'] is defined, it sets config['token'] to the value of config['auth_token'] [0] (which doesn't exist in my case - so it's None)
2. Then _fix_backwards_project [1] overrides config['auth']['token'] with config['token'], so it deletes the correct token and sets it to None.

[0] https://opendev.org/openstack/openstacksdk/src/branch/master/openstack/config/loader.py#L1162-L1168
[1] https://opendev.org/openstack/openstacksdk/src/branch/master/openstack/config/loader.py#L788-L790

It impacts the octavia-dashboard, it can no longer connect to the OpenStack cloud (the 'None' token is rejected by keystone), we may workaround it by renaming the key 'token' to 'auth_token' in the auth dict (it would not be overwritten by 1.)