[clang] [llvm] [HLSL][SPIRV][DXIL] Implement `dot4add_i8packed` intrinsic (PR #113623)

[Vyacheslav Levytskyy via llvm-commits]

VyacheslavLevytskyy wrote:

Thank you @inbelic , @s-perron , @dneto0 , it makes sense to me.

https://github.com/llvm/llvm-project/pull/113623