Consider removing images with sampled == 0 to unify Shader and Kernel SPIR-V?

One of the long-term goals of the SPIR-V working group is to reduced deltas between the "compute" and "graphics" SPIR-V variants to simplify the specification and tooling. One of the current deltas relates to images, and specifically to the _Sampled_ operand to [OpTypeImage](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#OpTypeImage). Even though there is nothing in the SPIR-V specification specifically tying values of the _Sampled_ operand to Shader or Kernel capabilities, the [Vulkan SPIR-V Environment](https://registry.khronos.org/vulkan/specs/1.3-extensions/html/vkspec.html#VUID-StandaloneSpirv-OpTypeImage-04657) restricts _Sampled_ to the values of 1 (sampled image) or 2 (storage image), whereas the [OpenCL SPIR-V Environment](https://registry.khronos.org/OpenCL/specs/3.0-unified/html/OpenCL_Env.html#validation-rules) restricts _Sampled_ to the value 0, indicating that the image usage will only be known at run-time.

This issue is to track required changes to the SPIR-V LLVM Translator, were the SPIR-V working group to deprecate (and eventually remove?) support for _Sampled_ == 0 images.

In short, I think we would need the following changes:

* Read-only images will be assigned "Sampled == 1" since they may be used with a sampler.
* Write-only or read-write images will be assigned "Sampled == 2" since they will never be used with a sampler.
* When a "Sampled == 2" image is declared, the Image1D or ImageBuffer capabilities will need to be declared instead of (or in addition to) the Sampled1D or SampledBuffer capabilities.
* Depending whether "Sampled == 1" images work with OpImageRead, OpImageFetch may need to be generated instead.
* For a "Sampled == 1" image, generate OpImageQuerySizeLod with a fixed LOD equal to zero instead of OpImageQuerySize. OpImageQuerySize should continue to be generated for a "Sampled == 2" image.

It'd be great to develop a POC with these changes to ensure there are no unexpected complications.

No repository files, tests, or entry points are named. Start by reviewing the SPIR-V Translator behavior against the Vulkan and OpenCL validation rules linked in the issue. A useful proof of concept should cover sampled values 1 and 2, capability declarations, image read operations, and image-size queries without relying on Sampled == 0.

Written by the indexing model from the issue text.