[clang] [clang][deps] Extract service config into a struct (PR #181405)

[Qiongsi Wu via cfe-commits]

qiongsiwu wrote:

Also, this is technically doing the same work as https://github.com/llvm/llvm-project/pull/167964. So if we land this PR, I think we should close https://github.com/llvm/llvm-project/pull/167964. FYI @Bigcheese . 

https://github.com/llvm/llvm-project/pull/181405