[clang-tools-extra] issue-63565: community requested small QoL fix for more configurabili… (PR #108005)

[Nathan Ridge via cfe-commits]

HighCommander4 wrote:

> Is this okay!?

Yep. By the way, this was specified in the [original proposal](https://github.com/llvm/llvm-project/issues/63565#issuecomment-1975065771):

> Here's a concrete proposal for a config file syntax that would address this request, https://github.com/clangd/clangd/issues/1252, and supersede `--function-arg-placeholders`: add a new key **under `Completion`** called `ArgumentLists`, with the following supported values:





https://github.com/llvm/llvm-project/pull/108005