[clang-tools-extra] [Bazel][Clang Tidy] Include builtin headers with clang-tidy (PR #67626)

[Arthur Eubanks via cfe-commits]

aeubanks wrote:

my worry about baking in the resource dir for the bazel build is that it'll be tied to the bazel build directory structure implementation details, so it's likely that you can't copy the binaries around and create a toolchain out of it. if bazel users don't care about this, then that's fine, but it seems like a common use case to assemble a toolchain that resembles a toolchain built with CMake. that's why I think it'd be nice to explicitly copy files into a typical toolchain structure, and clang tools that rely on the default builtin headers relative path will all "just work"

or something along the lines of this patch where we symlink the headers (choosing relative directories in a more structured way if possible as mentioned earlier, otherwise this is fine if there's no cleaner way)

https://github.com/llvm/llvm-project/pull/67626