Allow custom debug visualisation to be disabled with a flag

[alt-romes]

By default, when #120 is merged, as long as you depend on a library like text or containers we will try to load a custom debug visualisation for it.

For instance, we'd see this for this `Map (Map Integer Integer) Integer:

However, it may be useful to look into the actual heap representation of these common datatypes.

It would be easy to add a flag which disables the custom-debug-view behavior (e.g. by returning Nothing rather than calling findHsDebuggerViewUnitId when that flag is set)