Add a NodeWithBlockEditor InterfaceType

[drewbaker]

I want to be able to do this:

        ... on NodeWithBlockEditor {
            blocks {
                name
                # etc...
            }
        }

There is a similar thing with NodeWithContentEditor already in core.

This is how another plugin is doing it:
https://github.com/wpengine/wp-graphql-content-blocks/blob/main/includes/Type/InterfaceType/ContentBlockInterface.php