[clang] [HLSL] Add IsMultiSampled HLSL resource attribute (PR #211125)

[Aaron Ballman via cfe-commits]

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@@ -5195,6 +5195,12 @@ def HLSLIsArray : TypeAttr {
   let Documentation = [InternalOnly];
 }
 
+def HLSLIsMultiSampled : TypeAttr {
+  let Spellings = [CXX11<"hlsl", "is_ms">];
+  let LangOpts = [HLSL];
+  let Documentation = [InternalOnly];
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AaronBallman wrote:

I see other HLSL attributes are doing this too but `InternalOnly` is documented as only being used when we explicitly do not want to document the attribute because it has no user-facing spelling. These all have spellings the user can use, so these all require actual documentation.

(I'm fine if that happens in a follow-up rather than holding up this PR, but I'd also be fine if this PR bites the bullet and starts adding documentation for just this new attribute.)

https://github.com/llvm/llvm-project/pull/211125