ShortcutPreference Toggle design (2/n)

- Removes edit shortcut disable condition.
- Shows "off" if user removes all items in edit dialog.
- Restores last time what user chosen options when show edit dialog.

Bug: 148989269
Test: Manually test
Change-Id: I105abda782999d38c92e3de9811e2fd378869e73
6 files changed