Hide the empty 'Add New' on the list table view

By setting the CPT label to false, we accomplish not showing the 'Add New' link label. However, in the list table view, `.add-new-h2`displays empty because it's not tied to `$post_new_file` like in the fork editor.

I propose we add a body class to the list table view, then hide via css versus just printing some inline css to hide it. Also allows for a targetable styling option for future use.