[clang] [llvm] Ast importer visitors (PR #138838)

[Balázs Kéri via llvm-commits]

https://github.com/balazske commented:

Code looks almost acceptable. I could not verify if the tests are sufficient (I am not familiar with this new syntax). Can you test this on large projects that use these types of expressions?

https://github.com/llvm/llvm-project/pull/138838