[llvm] [RemoveDIs][DebugInfo][IR] Add parsing for non-intrinsic debug values (PR #79818)

[Jeremy Morse via llvm-commits]

jmorse wrote:

> @jmorse might want to check he's happy with the overall approach now though

I'm fine with it, although we should be ready to adjust it if there's turbulence.

https://github.com/llvm/llvm-project/pull/79818