inspector: Fix surface transform regression

inspector: Fix surface transform regression

Ever since we added surface-to-widget transforms,
the autofading of the fps overlay did not work anymore,
since it was given the transient transform node, most
of the time.

Fix this by passing both the root of the node tree and
the node for the toplevel widget to prepare_render, and
hande the widget node to the overlays. Update the
affected overlays that need to have their positioning
adjusted.