[clang] [clang-tools-extra] [clangd] CodeCompletion surface param names if possible (PR #206716)

[Nathan Ridge via cfe-commits]

HighCommander4 wrote:

>   * `createCodeCompletionStringForDecl` this one calls the first function for C and C++ but for ObjC it calls `FormatFunctionParameter`directly, not sure how much imporatce we have for ObjC but technically I could add it.

This is operating on `ObjCMethodDecl` which is not a `FunctionDecl` so I don't think there's anything to do here.

https://github.com/llvm/llvm-project/pull/206716