[clang] [llvm] [AMDGPU] Add a new builtin type for image descriptor rsrc (PR #160258)

[Shilei Tian via llvm-commits]

shiltian wrote:

If it's just a struct, why add a built-in type? I don't see the need here. We have the buffer resource type because we use it as a regular pointer in the IR. For the Clang builtins, they can just use `v8i32`.

https://github.com/llvm/llvm-project/pull/160258