Artboard guides visible but without policies when child layer is selected

[iwehrman]

1. Create a new artboard document.
2. Select the artboard.
3. Drag in a guide to create an artboard guide.
4. Deselect all layers by clicking in the panel.
5. Select the child layer of the artboard.

Result: guide is visible, but has no pointer policy, and so can't be moved.

Secondary issue:

1. Create a new artboard.
2. Select the child layer.
3. Drag out an artboard guide.
4. Deselect all layers.

Result: the guide is hidden, but the pointer policies remain incorrectly.

CC @volfied

[iwehrman]

Fixed by #3738.