Add a shutdown Vulkan function to correctly free the Vulkan resources

[mamoniem]

When closing a Vulkan based application, there will be some validation errors due to the optick resources. Would be called like so:

void ShutdownVulkan()
{
#ifdef WITH_OPTICK
	OPTICK_GPU_SHUTDOWN_VULKAN();
#endif

//the rest of vulkan shutting down
}

this pull related to #121