macosx: Use accessibility description for input node path control items as...

macosx: Use accessibility description for input node path control items as path control item identifiers

The input node path control items are readable strings but can be used
as identifiers thanks to the fact the contain the path for the given
input node. This is a big ugly hack but we have no other option to make
input node path control items identifiable, as we receive different
instances from the nspathcontrol that are not our subclass

Signed-off-by: Claudio Cambra <developer@claudiocambra.com>