Missing scope parameter / Support for Simple OAuth2 6.x Drupal module

[Decipher]

Describe the bug
When using DruxtAuth with the Simple OAuth2 6.x Drupal module you get the following error:

{
error: "invalid_request",
error_description: "The request is missing a required parameter, includes an invalid parameter value, includes a parameter more than once, or is otherwise malformed.",
hint: "Check the `scope` parameter",
message: "The request is missing a required parameter, includes an invalid parameter value, includes a parameter more than once, or is otherwise malformed."
}

The issue is caused by DruxtAuth having no support or means to send scope settings.

To Reproduce
Steps to reproduce the behavior:

1. Setup DruxtAuth <-> Simple Oauth2 6.x site
2. ...
3. See error

Expected behavior
Have the ability to configure the scopes to be used alongside the existing Druxt Auth config.

Media
N/A

Your Environment (please complete the following information):
N/A

Additional context
N/A