Refactor config settings

What does this Merge Request do?

With this refactor the ConfigType objects are retained. This puts more responsibility in the classes and will make it easier later on to dump only the YAML values and validate the values when setting them.

This is a preparation for #939 (closed).

I think it also will address #950 (closed).

Merge Request checklist

• Tests added for new functionality. If not, please raise Issue to follow-up.
• This change is backward compatible. If not, please include steps to communicate to our users.
• Documentation added/updated, if needed.
• gdk doctor test added, if needed.