Descriptor Indexing Tests don't test conditionally accessing descriptors

[Jasper-Bekkers]

Hi,

We're in the wild seeing drivers that don't correctly deal with the following pattern in shaders:

if(handle.isValid()) {
     g_bindlessTable[handle].doStuff();
}

What certain drivers are doing is hoisting the descriptor access to before the isValid check which causes them to potentially access invalid memory (if the descriptor memory isn't backed yet for example).

[Jasper-Bekkers]

Note: our descriptors are setting the VK_DESCRIPTOR_BINDING_PARTIALLY_BOUND_BIT flag properly.