[llvm] [DirectX] Add `DXILRefineTypesPass` to prevent type promotion (PR #169384)

[Finn Plummer via llvm-commits]

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inbelic wrote:

This pass could also be made more general and added to the opt pipeline. However, registering a callback to infer types for backend specific instructions is a little more complex, so I have left it just for DirectX atm.

https://github.com/llvm/llvm-project/pull/169384