This patch adds rich test failure information to the Github output,
using the same library that is used for the buildkite pipeline.
Eventually I think we want to add more information like reproduction
information using the containers, but that is very divergent between
Github and Buildkite, so we probably want to wait until we've switched
over before doing that.
Reviewers: Keenuts, tstellar, lnihlen, DavidSpickett
Reviewed By: DavidSpickett, Keenuts
Pull Request: https://github.com/llvm/llvm-project/pull/133197
