vulkan: Add common implementations of GetDeviceQueue and DeviceWaitIdle

Now that everyone is inheriting from a common vk_queue struct, we can begin to build more common code. To start off, we'll have common vkGetDeviceQueue2 which, this time, isn't a wrapper! It's an actual implementation of a thing in common code. Imagine that! While we're here, we might as well throw in vkDeviceWaitIdle() since it's just a for loop.

Eventually, I'd like to unify VK_ERROR_DEVICE_LOST handling but that's something that should probably wait until another day. It's a bit trickier.