Move split functions from RecentsView to SplitSelectStateController

* Moving things out of RecentsView to avoid
dependency on a non-testable class
* Also helping prevent bloating RecentsView.java

Bug: 266482558
Test: Single Chrome instance in recents. Initiate split
with Chrome from workspace, tap on Chrome again in Taskbar,
ensure no crash.

Change-Id: I99ec704479ffaa860f4d80c2cb9f54182f31f41a

quickstep/src/com/android/launcher3/taskbar/TaskbarActivityContext.java

@@ -870,9 +870,9 @@ public class TaskbarActivityContext extends BaseTaskbarContext {
      * (potentially breaking a split pair).
      */
     private void launchFromTaskbarPreservingSplitIfVisible(RecentsView recents, ItemInfo info) {
-        recents.findLastActiveTaskAndRunCallback(
+        recents.getSplitSelectController().findLastActiveTaskAndRunCallback(
                 info.getTargetComponent(),
-                (Consumer<Task>) foundTask -> {
+                foundTask -> {
                     if (foundTask != null) {
                         TaskView foundTaskView =
                                 recents.getTaskViewByTaskId(foundTask.key.id);