Update dream settings UX to match latest mocks.

Updates:
- removed individual complication toggle
- added single toggle which enables/disables all supported complications
- updated colors to match mocks
- updated grid padding in order to line up with existing content. Note:
  this required more complex padding logic, using an item decorator to
  apply the padding only to inner grid elements.
- updated preview image, removing view nesting to make better use of
  ConstraintLayout
- Updated some strings to match mocks

Test: locally on device
Bug: 217555053
Change-Id: I573e5f4ed807cbe2ae9e00f183d402e6e3339590