Add number of contributors and main contributor with % owned to a file in the code hotspots tooltip

Problem to solve

Building on: https://gitlab.com/gitlab-org/gitlab-ee/issues/12683. We would like to see if a file is a code hotspots and many individuals are changing it or whether it's mostly 1 person and who is the most knowledgeable on it.

Intended users

Further details

Proposal

Permissions and Security

Documentation

Testing

What does success look like, and how can we measure that?

What is the type of buyer?

Links / references