[PATCH 0/7] MR106: vkd3d-shader/hlsl: packoffset() support.

[Francisco Casas (＠fcasas)]

Support manually packing constant buffer elements through the `packoffset(·)` syntax.

Support not included yet for simultaneously having semantics, `register(·)`, and `packoffset(·)`, for abnormalities such as:
```hlsl
Texture2D tex;

cbuffer buff
{
    float4 a : packoffset(c0);
    sampler sam : packoffset(c0) : register(s1) : SEMANTIC;
}

float4 main() : sv_target
{
    return tex.Sample(sam, float2(0, 0)) + a;
}
```
but this motivated the addition of the `hlsl_ir_var.offset_reservation` field instead of reusing `hlsl_ir_var.reg_reservation`.