Tutorial improvement for Accessibility shortcut (1/n).

Because can't save the value into setting keys for the service before version R, and in order to let tutorial dialog can get the consistent value, using alternative that each fragment with shortcut to must implement the new abstract method.

Bug: 148989018
Test: manual test
Change-Id: Iba2a7daa70eb00f0bba37317c9355531fbb77628