WM_operator_properties_filesel() allows C operators to set a display or sort
type for the File Browser to use. But the File Browser would always override
that because of an invalid _is_set() check. (The operators don't actually set
the value, they only set the property's default value.)
The only operator affected by this is "Recover Auto Save". It is supposed to
show a vertical list ordered chronologically. It used settings from the
previous File Browser usage before this patch.
This also makes it so operators that set a different display or sort type
don't change the sort or display type for the next File Browser operation.
So using "Recover Auto Save" entirely isolates display and sort type from other