[SPIR-V] SPV_EXT_descriptor_heap SPV_NV_ray_tracing accepted for AS heap stride but RayTracingNV capability not emitted for non-RT shaders

Description

When -fspv-extension=SPV_NV_ray_tracing is supplied, the stride pre-detection logic in SpirvEmitter.cpp marks the heap stride as acceleration-structure-aware and emits OpTypeAccelerationStructureKHR + OpConstantSizeOfEXT. However, CapabilityVisitor only adds the RayTracingNV capability when an RT instruction or execution model is visited. A compute shader compiled with SPV_NV_ray_tracing for heap AS access therefore emits the acceleration structure type without its enabling capability, producing invalid SPIR-V.

Fix

When the NV path is taken for heap stride computation, explicitly add the RayTracingNV capability, or exclude SPV_NV_ray_tracing from the set of extensions that trigger AS stride widening and document the omission.

References

• #8518, Copilot review comment

Start in SpirvEmitter.cpp and trace the stride pre-detection path for SPV_NV_ray_tracing, then inspect CapabilityVisitor to see how RayTracingNV is emitted. Verify the compute-shader heap access case described in the issue and confirm that the resulting SPIR-V has valid capability coverage, or that the extension is excluded and the omission is documented.