Support TaskOverlay with new TaskThumbnailView

- Also migrated getScaledInsets method into TaksOverlay

Bug: 335606129
Test: TaskOverlayViewModelTest
Test: TaskOverlayHelper is not tested because it should be a view-based screenshot test for TaskOverlay, which is currently impossible until we refactor TaskOverlay to MVVM
Flag: com.android.launcher3.enable_refactor_task_thumbnail
Change-Id: I07a8657ff0fe925d8021875310e3ed12a712ba7a