Fade in quick settings when shade opens

Call stack for previous QQS slide-in animation:
- PVC #setExpandedHeightInternal #onHeightUpdated
- NPVC #onHeightUpdated #updateHeader #updateQsExpansion
- QSFragment #setQsExpanson (which calls NPVC #getHeaderTranslation,
which moved QQS down/up on shade open/close)

This change uses the setup above and fades QQS in/out
depending on whether the header translation is 0.

Bug: 172289889
Test: open shade, qqs fades in
      close shade, qqs fades out

Change-Id: I5b48a450cc2da6dab8c997c9a6a395d54c2b9067