Delay desktop mode visual indicator update for across display drag

When dragging a task near the edge of a display towards an adjacent
display, the visual indicator could show and disappear rapidly. This
could be visually jarring before the user fully committed to a
cross-display drag or snapping action.

This commit introduces `VisualIndicatorUpdateScheduler` to manage
updates for the desktop mode visual indicator onDragPositioningMove,
which decides whether to update the indicator immediately or delay the
update based on the indicator type and topology.

Bug: 389868684
Test: atest VisualIndicatorUpdateSchedulerTest DesktopTasksControllerTest
Test: go/cd-smoke
Flag: com.android.window.flags.enable_connected_displays_window_drag
Change-Id: I98a98de0728178871767a88f5f1d624da6a6d3c2