[HLSL] Add missing Shader Model 6.0 availability for wave intrinsics (#189445)

Depends on PR #188814 to be merged first.

This PR fixes Shader Model availability for HLSL wave intrinsics so that
they all require at least SM 6.0.

Furthermore, there wasn't an easy way to specify Shader Model 6.0
availability while maintaining the requirement for Shader Model 6.2 when
16-bit types is enabled and the overload uses half types.
To fix the issue, this PR extends `_HLSL_16BIT_AVAILABILITY` to accept a
3rd optional argument that specifies the Shader Model availability when
16-bit types is disabled.

Example:
```hlsl
// If 16-bit types is enabled, require SM 6.2. Else, require SM 6.0 otherwise.
_HLSL_16BIT_AVAILABILITY(shadermodel, 6.2, 6.0)
_HLSL_BUILTIN_ALIAS(__builtin_hlsl_wave_active_all_equal)
__attribute__((convergent)) bool WaveActiveAllEqual(half);
```

The new `hlsl_alias_intrinsics_gen.inc`:
https://gist.github.com/Icohedron/a6e88efd56de384659efd3314c43851f

Assisted-by: GitHub Copilot