[llvm] [Passes] Enhance `--print-pipeline-passes` (PR #202892)

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

@rnk Marking this as fixing #200926. It's not exactly YAML, but I think the indentation is what we actually care about for readability.

https://github.com/llvm/llvm-project/pull/202892