Lock work tasks from SystemUI instead of ActivityStarter

By adding an onTaskProfileLocked(taskId, userId) RPC to
TaskStackListener and routing that through to a new WorkLockController.

Bug: 31001762
Test: //tests/PoApi/src/com/google/android/afwtest/poapi/WorkChallengeTest
Change-Id: I3fd28e6926c3f928e78b3c6ce0fe27413617695f

core/java/android/app/ITaskStackListener.aidl

@@ -95,4 +95,11 @@ oneway interface ITaskStackListener {
      * perform relevant animations before the window disappears.
      */
     void onTaskRemovalStarted(int taskId);
+
+    /**
+     * Called when the task has been put in a locked state because one or more of the
+     * activities inside it belong to a managed profile user, and that user has just
+     * been locked.
+     */
+    void onTaskProfileLocked(int taskId, int userId);
 }

core/java/android/app/TaskStackListener.java

@@ -74,4 +74,8 @@ public abstract class TaskStackListener extends ITaskStackListener.Stub {
     public void onActivityRequestedOrientationChanged(int taskId, int requestedOrientation)
             throws RemoteException {
     }
+
+    @Override
+    public void onTaskProfileLocked(int taskId, int userId) {
+    }
 }