Returns whether the Vulkan loader and an ICD have been found.
This function returns whether the Vulkan loader and any minimally functional ICD have been found.
The availability of a Vulkan loader and even an ICD does not by itself
surface creation or even instance creation is possible. Call @ref
glfwGetRequiredInstanceExtensions to check whether the extensions necessary
surface creation are available and
check whether a queue family of a physical device supports image
GLFW_TRUEif Vulkan is minimally available, or