[clang] [HLSL] Add HLSL 202y language mode (PR #108437)

[Chris B via cfe-commits]

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@@ -12397,6 +12397,9 @@ def warn_attr_min_eq_max:  Warning<
 def err_hlsl_attribute_number_arguments_insufficient_shader_model: Error<
   "attribute %0 with %1 arguments requires shader model %2 or greater">;
 
+def ext_hlsl_auto_type_specifier : ExtWarn<
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llvm-beanz wrote:

No, I think we should just allow and warn on using extensions, that matches generally how Clang handles them unless you pass `-pedantic-errors` which switches all the extension warnings to errors.

https://github.com/llvm/llvm-project/pull/108437