inspector: Make the recorder node list use a ListView

inspector: Make the recorder node list use a ListView

It's quite a bit faster now, but the code is also a bit more awkward.

Pain points:

- GtkTreeListModel cannot be created in UI files because it needs
  a CreateModelFunc.
  Using a signal for this doesn't work because autoexpand wants to
  expand the model before the signal handler is connected.

- The list item factory usage is still awkward. It's bearable here
  because the list items are very simple, but still.