Initial commit of new split screen work.

TODO:
* Extract out common elements in TaskShortcutFactory.MultiWindowFactory
for commonalities between new and old way of
invoking split screen
* Integrate with WM APIs (b/182002789)
* Write tests for SplitSelectStateController

Bug: 181704764

Change-Id: Ice35adb4ea82897f5e2433dc9b93a549f3d511b5

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

@@ -86,8 +86,8 @@ public class LauncherRecentsView extends RecentsView<BaseQuickstepLauncher>
     }
 
     @Override
-    public void init(OverviewActionsView actionsView) {
-        super.init(actionsView);
+    public void init(OverviewActionsView actionsView, SplitPlaceholderView splitPlaceholderView) {
+        super.init(actionsView, splitPlaceholderView);
         setContentAlpha(0);
     }