[llvm] [DirectX] Updating DXContainer Yaml to represent Root Signature 1.2 (PR #159659)

[Finn Plummer via llvm-commits]

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@@ -74,6 +74,7 @@ struct StaticSampler {
   uint32_t ShaderRegister;
   uint32_t RegisterSpace;
   dxbc::ShaderVisibility ShaderVisibility;
+  uint32_t Flags;
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inbelic wrote:

nit:
```suggestion
  // Version 3 onwards:
  uint32_t Flags;
```

https://github.com/llvm/llvm-project/pull/159659