Correctly handle pre-instance functions

[solidpixel]

Vulkan has a small number of functions that are special and handled by the loader.

• https://github.com/KhronosGroup/Vulkan-Loader/blob/main/docs/LoaderLayerInterface.md#pre-instance-functions

These use a different style of intercept than normal intercept functions, and do not layer in the same way. We currently treat them like normal intercepts, which means that things crash if you try to use the intercept with multiple layers installed because the function in the "layer below" is strange and doesn't behave like a driver ...

It's not clear if the Android loader implements the *Chain intercepts at all?

It's not clear that the Khronos VVL implement these correctly either KhronosGroup/Vulkan-Loader#1487

[solidpixel]

PR #53 disables next-layer queries using vkEnumerateInstanceLayersProperties(), but Android doesn't implement the specified way to do this so we cannot reliably query available extensions for multi-layer scenarios.