[clang] [clang][Diagnostics] Highlight code snippets (PR #66514)

[Timm Baeder via cfe-commits]

tbaederr wrote:

> The only thing we need to make sure is that highlighting isn't done in CI/ redirected output

It now respects `DiagOpts->ShowColors`, so that should work. But I guess you're talking about a test. :)



https://github.com/llvm/llvm-project/pull/66514