Fix split shade issues when going from portrait expanded quick settings

Fixes a couple of issues with the split shade when
starting from normal shade with expanded quick
settings to split shade:

* Notifications are not scrollable
  updateQsState() wasn't called when switching between
  normal shade <-> split shade. It calls setScrollingEnabled
  which is based on whether quick settings in full screen
  or not (basically are we in split shade or not).

* Footer is not visible
  There was a recent change that hides footer when
  quick settings expanded to avoid animation issues.
  We don't need this for split shade, so added a check
  so we don't hide them in split shade.

* Notifications are not collapsed into shelf
  Stack height was not updated when quick settings
  are expanded, so the end of the stack was outside
  of the screen bounds. Added exception for non-fullscreen
  quick settings to update the height.

* Notification stack is clipped incorrectly
  This is especially visible when swiping quickly,
  you can see that 'manage'/'clear all' buttons
  go outside of the shade background.
  Updated clipping calculation so notification background
  doesn't add corner radius to the coordinates by default
  and we add bottom margin to calculate the bottom
  part of the clipping rectangle.

Bug: 222699879
Test: expanding/closing quick settings and switching
  between splitshade/non-splitshade => checking that
  the shade is rendered correctly
Change-Id: Ieb9a8dddccf08f5b333a5065d78694278ca5ed55