[clang] [HLSL] Adjust resource binding diagnostic flags code (PR #106657)

[Damyan Pepper via cfe-commits]

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@@ -480,6 +480,9 @@ struct RegisterBindingFlags {
 
   bool ContainsNumeric = false;
   bool DefaultGlobals = false;
+
+  // used only when Resource == true
+  llvm::dxil::ResourceClass ResourceClass = llvm::dxil::ResourceClass::UAV;
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damyanp wrote:

Along with this, the various SRV, UAV, CBV, Sampler flags now seem redundant with ResourceClass.  Are these flags only valid when UDR is set?  

If that's the case then I wonder if this might be better expressed as a `std::variant`?

https://github.com/llvm/llvm-project/pull/106657