v3dv: implement VK_KHR_device_group
This is fairly straight forward since we only support one device group with one physical device, however, there is a bunch of additional functionality that is included with this extension, like vkCmdDispatchBase and interactions with VK_KHR_swapchain that we need to implement.
For the interactions with KHR_swapchain, there are tests in CTS: dEQP-VK.wsi.*.swapchain.create.image_swapchain_create_info
that will crash due to a bug in the tests (they use KHR_bind_memory2 without enabling it, which will only work on Vulkan 1.1 implementations. I filed an issue to Khronos to address this.