[clang] [HLSL] Add availability attributes to texture sample methods that require implicit derivatives (PR #212846)

[Finn Plummer via cfe-commits]

================
@@ -168,6 +168,7 @@ class BuiltinTypeDeclBuilder {
                          QualType ElementTy,
                          AccessSpecifier Access = AccessSpecifier::AS_private);
   QualType getGatherReturnType();
+  BuiltinTypeDeclBuilder &addDerivativeAvailability(StringRef MethodName);
----------------
inbelic wrote:

nit:

```suggestion
  BuiltinTypeDeclBuilder &addImplicitDerivativeAvailability(StringRef MethodName);
```

https://github.com/llvm/llvm-project/pull/212846