[llvm] [clang] [WebAssembly] Refactor Wasm Reference Types as TargetExtType (PR #71540)

[Thomas Lively via cfe-commits]

https://github.com/tlively commented:

Very cool! LGTM so far. It's really nice that we can delete that entire pass out of the backend. Where can I read more about these new target extension types?

https://github.com/llvm/llvm-project/pull/71540