Crop Desktop TaskThumbnailView according to its intersection with parent

- Override TaskThumbnailView's outline bounds to be the Rect that the view intersect with parent, so it draw corner radius around the intersection, to match the corner radius behavior in live tile
- This is not fixed in TaskThumbnailViewDeprecated as it doesn't have an outline implemenation, and it's too complicated to rewrite that as a bugfix

Fix: 379881502
Flag: com.android.launcher3.enable_refactor_task_thumbnail
Flag: com.android.window.flags.enable_desktop_recents_transitions_corners_bugfix
Test: OverviewDesktopTaskImageTest
Change-Id: I67d7e6a05b15f0f651c8ec71f33ca1e02d662b06