[REQ] generate constants with OAuth scopes

Is your feature request related to a problem? Please describe.

As a generated API user I want to reference to oauth scopes defined in the open api specification.

Describe the solution you'd like

The generator is aware of the available oauth scopes - it lists them in README.md.
It would be very useful to have a utility class that lists these scopes as string constants, so that they can be referenced by an API user. For example in java it could look like:

public class OAuthScopes {

    /**
    * scope description
    */
    public static final String SCOPE_AS_JAVA_CONSTANT = "actual.scope.name";
    /**
    * another scope description
    */
    public static final String ANOTHER_SCOPE = "another.scope";

    public static final List<String> ALL_SCOPES = List.of(
        SCOPE_AS_JAVA_CONSTANT,
        ANOTHER_SCOPE
    );
}

Describe alternatives you've considered

In theory one could just create a custom template to achieve this. However, due to mustache limitations the scope constant name would have to be defined in the scope data model on the generator side. As for now there is only scope name (scope) and description in the model (and of course the "hasMore").

Additional context

https://oauth.net/2/scope/

Start with README.md and trace how the generator's scope data model exposes scope names and descriptions to templates, including the existing hasMore field. Define the generated Java output's constants and ALL_SCOPES collection, then verify that scope names, Java constant names, and descriptions are represented in generated clients.