[clang] [llvm] [HLSL][DXIL][SPIRV] Create llvm dot intrinsic and use for HLSL (PR #102872)

[Thorsten Schütt via cfe-commits]

tschuett wrote:

Please advertise your achievements: https://github.com/llvm/llvm-project/blob/main/llvm/docs/GlobalISel/GenericOpcode.rst
Please add the intrinsics with semantics to the langref: https://github.com/llvm/llvm-project/blob/main/llvm/docs/LangRef.rst
@nikic will review
Please protect against misuse of your achievements: 
https://github.com/llvm/llvm-project/blob/main/llvm/lib/CodeGen/MachineVerifier.cpp


https://github.com/llvm/llvm-project/pull/102872