[clang] [clang-tools-extra] clangd: Extend reference search with constructor calls through forwarding (PR #169742)

[Nathan Ridge via cfe-commits]

https://github.com/HighCommander4 requested changes to this pull request.

Took an initial review pass through the patch.

However, I'm also seeing this version of the patch be crashy when used on a real codebase. Will see if I can get a stack trace.

https://github.com/llvm/llvm-project/pull/169742