[llvm] [GitHub] Add workflow to check author's commit access on new PRs (PR #123593)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 commented:

Haven't looked in depth at the code yet, but would it make more sense to split this into a separate workflow that triggers on `pull_request_review`?

I think labelling/writing a comment pinging the reviewer who approved the PR (maybe after checking the reviewer is a member of the LLVM org) that the author needs someone else to merge their PR could help streamline this even more.

https://github.com/llvm/llvm-project/pull/123593