Fling shade open with overscroll

By adding space before sections.
- Propagate section padding from PVC to AmbientState.
- NPVC translates QSFrame down by section padding
- StackScrollAlgorithm adds section padding above section headers

Bug: 172289889
Test: visual

Change-Id: I7cb1438fbe83b4e82c95ea8b3a471c7f6adfcaf1