[llvm] [DirectX] Get resource information via TargetExtType (PR #119772)

[Helena Kotas via llvm-commits]

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

LGTM! Lots of code churn, but fairly easy to follow. One small suggestion related to cbuffers which can be addressed later. 

https://github.com/llvm/llvm-project/pull/119772