feat(previews):disabling native WP previews

[moonmeister]

Given that there is a toggle for enabling previews, I somewhat expect the preview button to be gone from places it's not enabled.

It makes sense that some post types might need classic WP previews if the site is doing some kind of hybrid approach.

But maybe having the option to hide previews in some cases would be appropriate? Maybe a shared setting that enables or disables classic WP previews globally that can then be overridden on a per-post-type basis.