[clang] [clang][deps] Don't treat ObjC method args as module directives (PR #97654)

[Argyrios Kyrtzidis via cfe-commits]

akyrtzi wrote:

Could you test the change with a unit test in `DependencyDirectivesScannerTest.cpp` instead? It would be orders of magnitude more lightweight, execution wise, than a whole new lit test.

https://github.com/llvm/llvm-project/pull/97654