[clang] [llvm] [HLSL] Implement Texture2D::operator[] (PR #186110)

[Helena Kotas via cfe-commits]

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

Looks good, just a couple of nits. And please update the typos in the PR description (Implments, chagne). Thanks! :) 

https://github.com/llvm/llvm-project/pull/186110