[clang] [HLSL] Add Append/ConsumeStructuredBuffer definitions to HLSLExternalSemaSource (PR #113643)

[Justin Bogner via cfe-commits]

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bogner wrote:

I'm not entirely convinced that these AST tests that are all more or less duplicates of each other are really worth it for every single buffer type. They aren't easy to read or update and they vary from one another by literally just a few characters. I wonder if we should have one AST test for buffers in general and a more limited set that makes sure we're not way off base for the types of buffer that aren't represented in that one...

https://github.com/llvm/llvm-project/pull/113643