[clang] [Clang] Warn against unused parameters in C++ coroutines with `-Wunused-parameters` (PR #70567)

[Yuxuan Chen via cfe-commits]

yuxuanchen1997 wrote:

@ChuanqiXu9 , I just updated the PR. Do you mind checking if using a `RecursiveASTVisitor` is appropriate for this? I am a first time contributor and would appreciate more feedback. Thank you. 

https://github.com/llvm/llvm-project/pull/70567