Code monitors: add stable webhook payload
Created by: camdencheek
This adds a stable payload for a code monitor generic webhook in replacement of the placeholder "just dump everything we have as JSON."
I've created a separate type because there are some fields (like database IDs) that we don't want to expose to the user, and this allows us to evolve the webhook payload independently of our search results.
Fixes #27155 (closed) Fixes #30414 (closed) Closes #26824 (closed) Closes #10212
Test plan
Covered by unit tests. See goldenfiles for examples of payloads.