Clean up admin menu

The idea is to keep the admin interface clean and not clutter the left admin menu. The plugin settings page could be moved to Settings > Kadence Blocks and the Custom Icons admin page can be put "behind" a button just as the "Lottie Animations" admin page. That leaves the "Form Entries" page, which makes sense to keep in the admin menu, but maybe higher up under Comments? this would give the plugin a much more native/integrated feel…