[FR] Add ref to search results

[steinybot]

I would like POST /api/find_references to return the ref in the response and then be able to call GET /api/source to get the contents of the file with that ref.

I have some workflows that will perform searches and then lookup the contents later but if the code changes between then and when I get the contents those results do not match up.

All search responses should include refs.

[brendan-kellam]

@steinybot thx for raising. To clarify, is the suggestion to include the commit SHA per file s.t., you have a stable reference to call /api/source later? If so, I think that is a reasonable request, and probably something we want to return on all of our search & navigation apis.