Add 'session' to generate inventory method
Add 'session' to generate inventory method

Adds session to the method arguments and set it
when instanciating the TripleoInventory class.

The inventory from neutron resources code added in
https://review.opendev.org/765902 relies on the
session to create a network service client.

Partial-Implements: blueprint network-data-v2-ports
Change-Id: Ic4bac7ebee763fb39ff2951807775e464f3ad681

openstack/tripleo-common,openstack/tripleo-common