[HLSL][SPIR-V] Add Vulkan to target triple (#76749)

Add support for specifying the logical SPIR-V target environment in the
triple as Vulkan. When compiling HLSL, this replaces the DirectX Shader
Model with a Vulkan environment instead.

Currently, the only supported combinations of SPIR-V version and Vulkan
environment are:
- Vulkan 1.2 and SPIR-V 1.5
- Vulkan 1.3 and SPIR-V 1.6

Fixes #70051