Remove ownership of SDL's vulkan-surface

This surface is managed by SDL itself, so there is no need to keep it in
a Unique handle for us to delete.  Fixes the bug where vulkan crashes
during shutdown.

include/renderer_vk/renderer_vk.hpp

@@ -10,7 +10,7 @@ class RendererVK final : public Renderer {
 	vk::UniqueInstance instance = {};
 	vk::UniqueDebugUtilsMessengerEXT debugMessenger = {};
 
-	vk::UniqueSurfaceKHR surface = {};
+	vk::SurfaceKHR surface = {};
 
 	vk::PhysicalDevice physicalDevice = {};