[llvm] [workflows] Split pr-code-format into two parts to make it more secure (PR #78216)

[Tobias Hieta via llvm-commits]

https://github.com/tru commented:

Thanks for working on this. I like the idea of having a reusable workflow that can write comments to issues and PRs so that future workflows can just "hook-in" to that. Will make it a lot easier when we want to add more in the future.

There are some smaller issues that needs to be addressed, and I think it should be tested somewhere first. Also make sure to correctly format the python code.

https://github.com/llvm/llvm-project/pull/78216