Add TaskContentView parent to TaskThumbnailViewHeader and TTV

- Add TaskContentView parent view
- Extract TaskThumbnailViewHeader logic and any related state out of
TaskThumbnailView and move to TaskContentView
- Use vertical LinearLayoutManager to hold the TaskThumbnailViewHeader
and TaskThumbnailView
- Rename TaskThumbnailViewHeader to TaskHeaderView. Rename xml and state
 similarly

Bug: 397889146
Flag: EXEMPT. Refactor
Test: Refactoring CL. Existing unit tests still pass.

Change-Id: Ie31f35c6617aab272f984a6beb3e4cb8f58e3ce9