Always recreate TaskbarActivityContext

- Add ENABLE_TASKBAR_NO_RECREATION flag
  When the flag is turned on,
  * Always destroy and recreate
  * Move task bar drag layer lifecycle from TaskbarActivityContext to TaskbarManager
  * Wrap the drag layer into a fullscreen root view

Note that in order to preserve the window across multiple TaskbarActivityContext creations, the inset types and ids must stay the same, so it's extracted out.

Bug: 274517647
Test: Fold and unfold a few times. Use a few applications. Make sure the task bar is visible and in the right place (tested with ENABLE_TASKBAR_NO_RECREATION and FLAG_HIDE_NAVBAR_WINDOW both on, both off, and one on and one off)
Change-Id: Ic3f0aa3d056fe178a53b76b2ad6cc6b9bffd5898