Directly list related files in the magician comment on TPG prs.

[ScottSuarez]

Background

Github action bot auto comments on PRs to upstream the change.
#14570 (comment)

What kind of contribution is this issue about?

TPG prs

Details

Since we generate these files it should be relatively easy to keep a manifest and point the user directly to the file they need to edit... minor usecase but nice QoL improvement. I expect this would take 1 week of work

[rileykarson]

This is pretty easy when it comes to third_party files but pretty hard when it comes to generated ones, if we need to reference custom code. Assigning size based on that scope.