Add setFrameTimeline() call for task drag transaction.

Also verify that VeiledResizeTaskPositioner#onDragPositioningMove()
runs on the shell main thread - so we use the correct Choreographer
instance for setFrameTimeline.

Test: manual - checked perfetto traces
Flag: com.android.window.flags.enable_desktop_windowing_mode
Bug: 362480907
Change-Id: I69fc20082ca1073ba68ce28283405dffb6bd7162