OpName is wrong when using GL_EXT_descriptor_heap

If I go

```glsl
layout(descriptor_heap) buffer A { uint a; } heap_a[];
void main() {
heap_a[0].a = 0;
}
```

I get

```
pName %resource_heap "resource_heap"
```

which is not helpful at all

If you go

```
layout(descriptor_heap) buffer A { uint a; } heap_a[];
layout(descriptor_heap) buffer B { uint b; } heap_b[];
void main() {
heap_a[0].a = 0;
heap_b[1].b = 0;
}
```

It shares the same `OpUntypedVariableKHR` (and name) making it not possible to figure out which variable caused the issue.

Even if you argue "this should be done in ShaderDebugInfo", sure, but going `-gVS` currently provides no information