[FEATURE] Support search summary in comparison tool in playground

[sean-zheng-amazon]

Is your feature request related to a problem?

We are building QA summary based search using search pipeline. We want to use the search comparison tool to show the difference between that and normal searches. Can we add support to QA search into the comparison tool?

What solution would you like?

Basically we need to highlight the summarized answer and display the list of documents that used to summarize the answer. See attachment for details.
(to be updated)

What alternatives have you considered?

This could also be done via client side script but not as convenient.

Do you have any additional context?

Add any other context or screenshots about the feature request here.