[llvm] [DirectX] Implement the DXILCBufferAccess pass (PR #134571)

[Justin Bogner via llvm-commits]

bogner wrote:

> I'm seeing a pretty large regression in the DML shaders that are able to compile in the form `Load of {{.*}} is not a global resource handle`.

I looked into this and every case that regresses errors in the frontend if we implement https://github.com/llvm/llvm-project/pull/135909. Unfortunately there are a lot of uses of implicit bindings in that set of shaders, so it isn't exercising much of this code at all.

https://github.com/llvm/llvm-project/pull/134571