The neutron.object.utils module was rehomed into neutron-lib with
https://review.openstack.org/#/c/557809/
This patch consumes it by removing the neutron.objects.utils module
and corresponding test module, updating the contributor internals for
objects and using lib's version of the module.
NeutronLibImpact
Change-Id: If53d0ad660851275462d2641ed1829cdb4c32d05