Improvements to TaskbarDividerPopupView

- Close Animation improvement for popup.
- Popup location changed to  16dp above the taskbar view.
- Support for disabled state when user is in 3-button mode. (design changes to come in separate cl)

Test: Manual
Bug: 265170176
Flag: LEGACY ENABLE_TASKBAR_PINNING DISABLED
Change-Id: I9c91e6eb2b29c85433ba1c3d34505f0519448a6f