Folder icon polish.

- Increase the overlap between the preview items and the background
  so that it appears more intentional (lots of reports of users
  thinking that its a bug)
- Fix bug where clip path was still clipping icons when
  dragging and swiping to home.

Bug: 193701705
Bug: 191225536
Test: test 2 icon, 3 icon, and 4 icon folders
      close folder on 2nd page, ensure clipping
      ensure no preview items are clipped in drag view
      ensure no preview items are clipped in swipe up to home
      test 2x2, 3x3, 4x4, 4x5, and 5x5 grids to ensure no clipping
      of folder icons
      drag and drop folder in and out of hotseat
      create folders (2 icon, 3 icon, 4 icon)

Merged-In: Id49bae33438e10248bef05450d7e2c92c2140748
Change-Id: Ic3708bd402704f0a6f57ae5315ef602e2bbc6d82