Draft: effects/overview: Add keyboard navigation support to DesktopBar

1. Left: Shift focus to the left desktop. If the focus is on the 1st desktop, shift focus to the new desktop button.
2. Right: Shift focus to the right desktop. If the focus is on the new desktop button, shift focus to the 1st desktop.
3. Home: Shift focus to the 1st desktop.
4. End: Shift focus to the new desktop button.
5. Return/Enter/Space:
   1. If the focus is on the new desktop button: Trigger the action.
   2. If the focus is on the desktop: Return/Enter activates the desktop, and Space enters the edit mode.
6. Delete: Remove the desktop that has focus.
7. Tab: When in editing mode, pressing Tab will switch focus to the next text field.

BUG: 445369