Add split support for 3P launcher

* Copied logic mostly from
Base/RecentsViewStateController
* There's one KI crash specific to 3P
(b/209694087)
* Swipe to home animation is TODO, but
then again it also seems incorrect for
full-screen app. 3P has many cosmetic issues
throughout.

Bug: 195607777
Test: Tested w/ Nova launcher with grid
and non-grid, able to invoke split screen with
same animations as 1P launcher

Change-Id: I35a1bc92a51caccac4214289e614000cd47bb503

quickstep/src/com/android/quickstep/views/LauncherRecentsView.java

@@ -168,15 +168,4 @@ public class LauncherRecentsView extends RecentsView<BaseQuickstepLauncher, Laun
         super.initiateSplitSelect(taskView, stagePosition);
         mActivity.getStateManager().goToState(LauncherState.OVERVIEW_SPLIT_SELECT);
     }
-
-    @Override
-    protected void onOrientationChanged() {
-        super.onOrientationChanged();
-        // If overview is in modal state when rotate, reset it to overview state without running
-        // animation.
-        setModalStateEnabled(false);
-        if (mActivity.isInState(OVERVIEW_SPLIT_SELECT)) {
-            onRotateInSplitSelectionState();
-        }
-    }
 }