Grab sensor: "Hovered" output for secondary imps

Currently, the secondary imp is completely ignored when it comes to hovering over collidable/grabbable sculpts. So other more complex and less reliable means must be used to figure out if the secondary imp is hovering over a sculpt.

While we cannot grab with the secondary imp for engine reasons (as discussed on a stream in the past)... the grab sensor's "hovered" output could still give us a signal that the secondary imp is hovering over something to better allow us to make use of it in our games.

For example, the output from this setting could be a 2-numbers value, with A being "the primary imp is hovering" and B being "the secondary imp is hovering." This should work fine for most logic, though may cause issues. So alternatively we could simply have a new "Secondary hover" output instead to make things explicit.