[clang] [llvm] [ci] New script to generate test reports as Buildkite Annotations (PR #113447)

[David Spickett via cfe-commits]

DavidSpickett wrote:

I have updated this PR to include marking the option as hidden. If folks would be ok with that approach, I will break this up into individual parts for review and landing separately.

If no, I will work more on the lit wrapper approach.

@boomanaiden154 what do you think to that plan?

https://github.com/llvm/llvm-project/pull/113447