title: Drag and drop with pinch zoom doesn't work as expected
body: <p>In the zoomed mode for pinch-zoom the drag doesn't align properly with the mouse pointer.</p>
  
  <p>I've detailed the problem here:<a href="https://stackblitz.com/edit/angular-t7hwqg" rel="nofollow noreferrer">https://stackblitz.com/edit/angular-t7hwqg</a></p>
  
  <p>I expect the drag to work same way irrespective of the zoom.
  I saw in version 8 of angular material they have added @Input('cdkDragConstrainPosition')
  constrainPosition: (point: Point, dragRef: DragRef) => Point, which will solve my problem as in the zoomed mode I can write a custom logic to map the drag properly with pointer, but I can't upgrade to version 8 as there are other parts of the application with version 7.</p>
  
  <p>So if someone can suggest what can be done? Either somehow the drag can be modified and take into account the current amount of zoom, or if I can take 'cdkDragConstrainPosition' from version 8 of material and integrate into my current packages.</p>