Wizarding API

[JakobVogelsang]

The Wizarding is at the moment a key component. The problem here is that we use TemplteResult as a possible content type. This allows us to define a complex and powerful wizard. As a plugin author, I must load and extra dependency lit-element when working with TemplateResult as content. Therefore, we want to get rid of it with the downside that wizard-dialog can only be used for specific things only.