[clang-tools-extra] [clangd] Implement simple folding of preprocessor branches (PR #80592)

[Tor Shepherd via cfe-commits]

torshepherd wrote:

Darn, this was just closed last week as I put up an issue https://github.com/llvm/llvm-project/issues/110390 😭 

Clang-pseudo was just removed: https://github.com/llvm/llvm-project/pull/80081#issuecomment-2361060164 

Is the plan to refactor now and re-put this up?

https://github.com/llvm/llvm-project/pull/80592