BHV-15102: Display SCRIM when popup is shown

**Issue:** 
When multiple popup(having animation) are shown and hidden alternatively, the SCRIM behind the popup is hidden. The last popup which was made hidden, triggers the animation end event which hides the SCRIM.
**Fix:** 
SCRIM is made visible when the popup showing animation is complete.

Enyo-DCO-1.1-Signed-off-by: Anish Ramesan <anish.ramesan@lge.com>
Gotcha, thanks! I was hoping we wouldn't have to make unnecessary `showHideScrim` calls, as you're showing the scrim for the second popup, and then the first popup hides the scrim, and then second popup shows the scrim again.