Chaniging all-apps scrim

> Converting the scrim to View, to better avoid overdraw
> Overview and Spring loaded state have different scrim alpha
> When going from overview to all-apps, there is a color scrim drawn over the overview panel.
  The slef color is merged with this color to prevent overdraw, and the remaining screen is drawn
  with a cut-out round rect path

Bug: 79111591
Change-Id: I26801fde13dd6adb4b06110bbe8087e35cc31847