v3dv: expose VK_KHR_vulkan_memory_model

The spec for this is super dense, but my understanding is that the spir-v compiler translates all the semantics from this extension into NIR barriers we already support, so we don't really have to do anything specific.

We pass all the tests for this extension we can run (a bit over 1000 tests) and I checked we do run extra tests for each of the features we expose, so I think we can safely expose this.