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

[David Spickett via llvm-commits]

DavidSpickett wrote:

Example reports can be seen here - https://buildkite.com/llvm-project/github-pull-requests/builds/112660.

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