Add tests for Texture3D

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## References

- https://learn.microsoft.com/en-us/windows/win32/direct3dhlsl/sm5-object-texture3d
- Existing Texture2D offload tests: `offload-test-suite/test/Feature/Textures/Texture2D.*.test.yaml`

## Description

Add runtime GPU offload tests for `Texture3D`, mirroring the existing `Texture2D.*` test coverage. Texture3D uses `float3` locations, `int3` offsets, and `int4` Load locations (xyz + mip). Gather/GatherCmp are **not** available on Texture3D.

## Tasks

- [ ] **Add `Texture3D` to offload-test-suite `ResourceKind`**
- `offload-test-suite/include/Support/Pipeline.h` — add `Texture3D` to `ResourceKind` enum, update `isRaw()`, `isSampler()`, `isTexture()`, `isReadWrite()`, `isSampledTexture()`, and `ScalarEnumerationTraits`
- `offload-test-suite/lib/API/VK/Device.cpp` — add `Texture3D` cases: `VkDescriptorType`, `VkImageViewType` (`VK_IMAGE_VIEW_TYPE_3D`), image creation
- `offload-test-suite/lib/API/DX/Device.cpp` — add `Texture3D` cases: `D3D12_SRV_DIMENSION_TEXTURE3D`, SRV/UAV descriptor setup
- `offload-test-suite/lib/API/MTL/MTLDevice.cpp` — add `Texture3D` case for Metal texture type mapping

- [ ] **Write tests** (`offload-test-suite/test/Feature/Textures/`)
- `Load.test` — `Load(int4)` and `Load(int4, int3)` with offset
- `Sample.test` — `Sample(SamplerState, float3)` with offset and clamp overloads
- `SampleBias.test` — `SampleBias(SamplerState, float3, float)`
- `SampleGrad.test` — `SampleGrad(SamplerState, float3, float3, float3)`
- `SampleCmp.test` — `SampleCmp(SamplerComparisonState, float3, float)`
- `OperatorIndex.test` — `Tex[uint3]` subscript
- `mips.OperatorIndex.test` — `Tex.mips[mip][uint3]`
- `CalculateLevelOfDetail.test` — `CalculateLevelOfDetail(SamplerState, float3)`
- `Sampler.filter.test` — sampler min/mag filter behaviour
- `Sampler.address.test` — sampler address modes
- `Sampler.mips.test` — sampler mip selection