Matrix Intrinsic Implementation Requirements

[kmpeng]

• Implement the matrix api for the intrinsic in hlsl_alias_intrinsics.h/hlsl_intrinsics.h
• If applicable, update sema checks for the intrinsic in SemaHLSL.cpp to accept matrices
• Add matrix codegen tests to clang/test/CodeGenHLSL/builtins/<intrinsic>_mat.hlsl
• Add matrix sema tests to clang/test/SemaHLSL/BuiltIns/<intrinsic>_mat-errors.hlsl
• If the intrinsic maps to a DXIL opcode, add matrix backend tests to llvm/test/CodeGen/DirectX/<intrinsic>_mat.ll
• If the intrinsic maps to a SPIR-V intrinsic, add matrix backend tests to llvm/test/CodeGen/SPIRV/hlsl-intrinsics/<intrinsic>_mat.ll