[clang] [llvm] Reapply "[clang][deps] Add in-flight query caching to `DependencyScanningFilesystemSharedCache`" (#202804) (PR #202881)

[Felipe de Azevedo Piovezan via cfe-commits]

https://github.com/felipepiovezan approved this pull request.

This is a re-apply with a test fix, merging.

https://github.com/llvm/llvm-project/pull/202881