elementary: make sure that the model parent being used is always the fileselector.
Model provided by an item selection would have there parent being the current
model of the fileselector. Once that one is replaced by the item model, it would
automatically invalidate the model and break any further request. This lead to
a bug where you could only get into one directory before everything else
Reviewed-by: Marcel Hollerbach <firstname.lastname@example.org>
Differential Revision: https://phab.enlightenment.org/D8450