Add ansible-freeipa-tests inventory using podman

This inventory file is usable for the containers started with
infra/image/start.sh.

infra/image/inventory

+[ipaserver]
+ansible-freeipa-tests ansible_connection=podman
+
+[ipaserver:vars]
+ipaadmin_password=SomeADMINpassword
+ipadm_password=SomeDMpassword