title: Setting totalPages in Ag-grid pagination
body: <p>I am using Ag-grid with pagination.</p>
  
  <p>I am looking for a way to set the total number of pages for pagination with the <strong>count/pageSize</strong> way.</p>
  
  <p>The data should be loaded on event <strong>onPaginationChanged</strong></p>
  
  <p>Something like :  </p>
  
  <pre><code> this.gridOptions.api.setTotalPages = 10
  </code></pre>