Should update specific item instead of the whole list of the accessibility target.

Goal:
Avoid always involving notifyDataSetChanged() when any accessibility target is added. And then replace it with notifyItemInserted(), notifyItemRemoved(), and notifyItemChanged();

Actions:
1) Using the DiffUtil callback for updating the target feature list.
2) Fine-tuned the timing point of fade in/out effect.
3) Fine-tuned the setter/getter of the state description.

Fix: 252756133
Test: manual test
Change-Id: Iea848ece58bbc4b8c799a9dcb5c335331d6fd418