title: show header even when there is no data to show in admin on rest datagrid
body: <p>I am using admin-on-rest to display a list of data. In the Datagrid when there is no data coming from the response the Datagrid shows <strong>No results found</strong> . But I want to show the headers. is there anything like <strong>showHeader</strong> that I can pass to Datagrid as a prop . Since it is built on top of material-ui ,so i checked material-ui too.but no luck.</p>
  
  <p>Any help will be appreciated.</p>
  
  <p>Thanks</p>