MetaSRA metadata in search results

### Context

One of the goals for MetaSRA metadata would be to to make it searchable via the refinebio search api. We will want to be able to show why certain results show up for a specific query.

### Problem or idea

We need to figure out a way to return which MetaSRA metadata keys or values match a specific query in the search results. This is probably possible through a custom class or some meta data.

We should think about what the refinebio-frontend would like to consume but also consider how someone consuming the API directly would be able to automate against these results.

### Solution or next step

* Look at MetaSRA data for options to query/display that data
* Look at how to implement a class or middleware that modifies the default results to include something like a list of metasra key/value matches.