[SM6.9] Native Vector Support for Intrinsics Returning Vectors of Set Components and Variable Length

**Description**
DXIL vectorization should extend to elementwise operations where the return type and element types are not the same.

**Additional Context**
Draft implementation: https://github.com/pow2clk/DirectXShaderCompiler/commit/0a9cb89e97d2fecc0d737f712a5449e47ea8e609