Use separate layout for un-selected page previews

- Make remove icon more visible by removing the translucency in icon
- Replace remove and check icon by vectors
- unselected pages are now not faded out by being 50% translucent to the
  page shadow anymore, they are explcityly faded out by being 50% translucent
  to a defined background color
- No need for our own animations as the recyclerview does all the
  animations for us

Fixes: 28885729
Change-Id: I70d2db89c4124bf5ef528c65b5f79d189da43857