title: swimlane/ngx-datatable, how to disable checkbox on condition?
body: <p>I have 2 issues with swimlane/ngx-datatable.</p>
  
  <ol>
  <li>unable to control(enable or disable) the checkbox based on condition.</li>
  <li>group selection. I followed the below link but i am unable to check the group child when the parent is checked</li>
  </ol>
  
  <p><a href="https://github.com/swimlane/ngx-datatable/blob/master/demo/basic/row-grouping.component.ts" rel="nofollow noreferrer">https://github.com/swimlane/ngx-datatable/blob/master/demo/basic/row-grouping.component.ts</a></p>
  
  <p><a href="https://i.stack.imgur.com/8DPLw.png" rel="nofollow noreferrer">attaced the screenshot, check it</a></p>
  
  <p>thanks in advance</p>