[clang-tools-extra] [clangd] [C++20] [Modules] Introduce initial support for C++20 Modules (PR #66462)

[Qiongsi Wu via cfe-commits]

qiongsiwu wrote:

> The scanning failure is not expected and the ignored unused argument for -c is more or less expected.

> And we'd better fix them in clangd instead of changing the test since the test mimics actual compilation databases.

Thanks! I will open a Github issue. 

https://github.com/llvm/llvm-project/pull/66462