Cross fade escalation card when content changes.

Fixes: 30079520

Whenever escalation card needs to change content:
- Instead of rebuilding entire data set, rebuild just escalation data.
- Instead of notify entire data set change, only notify the position
  change for escalation card.
This triggers the cross-fade animation in RecyclerView's
DefaultItemAnimator.

Change-Id: Ia19593d852fa6a1c366aecf9330d8274d7295e85