[llvm] [Workflow] Expand code-format-helper.py error reporting (PR #69686)

[Ryan Prichard via llvm-commits]

rprichard wrote:

I noticed that `git-clang-format` also accepts a `--` argument before its file list, like darker does. Maybe we should add it for `git-clang-format`? It can be a separate PR.


https://github.com/llvm/llvm-project/pull/69686