SystemUI Split via TaskOrganizer

Use the early TaskOrganizer concepts to implement Split-screen
in system-ui.

This includes changes to both FW and SystemUI. The changes to
FW involve removing the use of split-screen specific behavior (like
minimize dock and direct ordering) and also reducing things that
care about primary vs secondary. It also changed ActivityStack
to inherit bounds from parent** when in split-mode so that sysui
only needs to manipulate the tile and/or reparent stacks to
effect their geometry.

This means a lot of layout logic moves to SystemUI. The bulk of
the work done in ActivityStack which is split-screen related is
moved into SplitDisplayLayout. This basically takes a snapshot of
display configuration and manages the sizes of splits and their
snap targets.

Intermediate dragging of divider bar now only moves root task leashes
around rather than talking to WM. This includes position as well
as crop (which used to be stack crop). Once the user releases
the divider bar, it will calculate (based on snaps) the new
root task sizes and update their configurations via
WindowContainerTransaction. Because the interim updates are only
on the leashes, no configuration updates occur until the end.

Entering/Exiting split-mode is now handled by SplitScreentaskOrganizer#
onTaskInfoChanged. This is effectively a state-machine that
looks at the current split task membership vs. previous and then decides
when to move things into/out-of split tasks and how to coordinate with the
DividerView.

Minimized dock is relegated to a purely system-ui concept. To
accomplish this, **the home *stack* is set to the minimizedhomebounds
by systemui. This means that it's relative position to its parent is
negative! This allows us to leave the split sizes constant, have
their children inherit the "actual" split sizes, but keep the
home stack unchanging in its minimized size. We just adjust the crop
negative to reveal it.

IME handling is done through the same mechanism as app-driven IME
animation... only Divider receives the control instead of the app.
This allows synchronized animation of split tasks with IME. To
account for insets, though, when IME is opened, the bottom stack
will be repositioned in WM.

Bug: 133381284
Test: Manual, use split-screen, rotate device, launch unresizable
      apps in split, use divider snap to close/maximize apps, etc.
Change-Id: I7133e151a1037c42b275b97857936437a7a6725f