GraphQL API: Tracking removed deprecated fields

Once a field is removed, we may want to list these somewhere, or otherwise keep track of them.

The following discussion from !39584 (merged) should be addressed:

• @.luke started a discussion: (+3 comments)

  Question

  Do you know what the process for GitLab is/should be for this to happen, or who the DRI would be for collating the deprecation data?

  Edit: this is just a meta-question because I'm curious, but we may not have the answer yet (and it doesn't necessarily need an answer yet).