[llvm] Set shader analysis flags EnableRawAndStructuredBuffers and ComputeShadersPlusRawAndStructuredBuffers for RWBuffers (PR #114449)

[Cooper Partin via llvm-commits]

coopp wrote:

Hopefully this PR helps validate my approach for setting these flags.  I have not figured out how to get strcuturedbuffers to work/be detected yet.  I thought I had the correct IR, but they are not being picked up for some reason.

I had this logic in the code which is not in this PR
```
// StructuredRWBuffer
  for (const ResourceInfo &RI : DRM.srvs()) {
    if (RI.getResourceKind() == ResourceKind::RawBuffer) {
      Flags.EnableRawAndStructuredBuffers = true;
      Flags.ComputeShadersPlusRawAndStructuredBuffers =
          (SP == Triple::EnvironmentType::Compute && SM.getMajor() == 4);
      break;
    }
  }
```

https://github.com/llvm/llvm-project/pull/114449