Implicit cast from float1 to inout float3 hits an assert for DXIL

Hello!

void bar(inout float3 param) {
}

[numthreads(1, 1, 1)]
void main() {
  float1 a = 0;
  bar(a);
}

$ dxc -T cs_6_6 -E main repro.hlsl
EmitNumericConversion can only cast between scalars or vectors of matching sizesdxc: DirectXShaderCompiler/tools/clang/lib/CodeGen/CGHLSLMS.cpp:4328: llvm::Value* ConvertScalarOrVector(clang::CodeGen::CGBuilderTy&, clang::CodeGen::CodeGenTypes&, llvm::Value*, clang::QualType, clang::QualType): Assertion `false && "EmitNumericConversion can only cast between scalars or vectors of " "matching sizes"' failed.
Aborted (core dumped)

This however is allowed and just warns for the implicit truncation.

void bar(inout float3 param) {
}

[numthreads(1, 1, 1)]
void main() {
  float a = 0;
  bar(a);
}

On the SPIR-V side, we accept this.

Reproduce the crash with the dxc command and repro.hlsl shown in the issue, then inspect tools/clang/lib/CodeGen/CGHLSLMS.cpp around line 4328 and the ConvertScalarOrVector assertion. Done means the float1-to-inout-float3 example no longer aborts during DXIL compilation and preserves the accepted implicit-conversion behavior described in the issue.