Merge "header-checker: replace llvm::Optional with std::optional" into main am: 42f592ef4f

Original change: https://android-review.googlesource.com/c/platform/development/+/2962957

Change-Id: I8b834248f7a4e05932343ef5ebb31b0c9f2c4547
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>