Fix Vulkan offload test suite setup to allow for wave size specification

Nobody has claimed this yet.

Right now, Vulkan ignores the specified WaveSize attribute in the HLSL.
In the device creation code, there is no mention of VK_EXT_subgroup_size_control to set the wave size based on the attribute in the HLSL.
So, when Vulkan is the IR target, the device will just use the default wave size.

This issue tracks updating the test infrastructure so that the wave size specified in the HLSL is properly referenced, or an error is raised if the device doesn't support it.

---

We have [various tests](https://github.com/search?q=repo%3Allvm%2Foffload-test-suite%20WaveSize%20path%3A*.test&type=code) that rely on the WaveSize attribute to control the wave size ("subgroup size" in Vulkan terms). Vulkan/SPIRV doesn't have an equivalent to this attribute, but instead has the VK_EXT_subgroup_size_control extension that can be used for the same purpose.

For this task we should:
* find a way to expose this via the pipeline yaml
* expose supported subgroup sizes that can be used in REQUIRES clauses.
* update the existing tests to use it

Start by locating the device creation code, pipeline YAML handling, and existing tests that use the WaveSize attribute. Trace how Vulkan test requirements are currently exposed, then update the infrastructure so subgroup-size support can be referenced and unsupported sizes produce an error. The existing WaveSize tests should pass using the new REQUIRES clauses.

Written by the indexing model from the issue text.