Allows the hierarchy operations in lock-task mode

For the hierarchy op :reparent-children-tasks/launch-task are skipped
currently. That makes the split-screen can not work in lock-task mode.

This CL allows the system to execute the reparent-children-task, launch
task and reorder hierarchy op if the tasks are not in lock-task
violation mode.

Bug: 199342537
Test: atest MultiWindowTests
Test: 1. Enter Kiosk mode
      2. Enter split-screen mode
      3. Check split-screen work properly
Change-Id: Ifdaa1d04b3370fce47a7400628e5881ae7a046bd