[clang] [HLSL] Codegen for indexing of sub-arrays of multi-dimensional resource arrays (PR #154248)

[Chris B via cfe-commits]

https://github.com/llvm-beanz approved this pull request.

I've put some really nitpicky comments with suggestions about code comments to align with LLVM coding standards (https://llvm.org/docs/CodingStandards.html#commenting), but otherwise this PR looks good.

https://github.com/llvm/llvm-project/pull/154248