[clang-tools-extra] [clangd] Re-land "support outgoing calls in call hierarchy" (PR #117673)

[Nathan Ridge via cfe-commits]

HighCommander4 wrote:

> I was trying to imply a knob like https://github.com/llvm/llvm-project/blob/main/clang-tools-extra/clangd/ClangdServer.h#L111. I don't think the knob needs to be exposed to end-users directly, only having programmatic access is fine initially.

Thanks, that is indeed quite a bit simpler.

I reworked the flag to be just a ClangdServer option, and plumbed it in explicitly, in https://github.com/llvm/llvm-project/pull/117673/commits/0aee7953ef1285bb327f20a01389e554fb44ffa8.

https://github.com/llvm/llvm-project/pull/117673