Accessibility fixes

1) Use a different content description for temporary new page
2) Use different accessibility description for add widget toast
3) Announce when an item is deleted
4) Announce when hovering over a drop target
5) Announce state during drag-n-drop and widget resize (similar to seekbar)

Bug: 23573321, 24057944
Change-Id: Icabb317625e70c78e11c0b4f99b9339172d93594