Fix ActivityEmbedding flicker when dragging freeform window

Before, when dragging freeform window without resizing,
TaskFragmentOrganizer would update the TaskFragment bounds to abosulte
bounds, which can have a racing condition when the freeform Task is also
repositioning.
Now, TaskFragmentOrganizer only set relative bounds, so that it won't
trigger unnecessary change transition.

Also, don't start change transition when the Task isDragResizing.

Bug: 256967281
Test: atest WMJetpackUnitTests:SplitPresenterTest
Test: atest WmTests:TaskFragmentTest
Test: atest WmTests:TaskFragmentOrganizerControllerTest
Test: manually verify dragging freeform with ActivityEmbedding
Change-Id: I87535036c9f69a7b50b2fe6bdf3e996ae73a8a64