Adds support for custom Placement configuration.

ansible/kolla-openstack.yml

ansible/roles/kolla-openstack/defaults/main.yml

...s/kolla-openstack/molecule/enable-everything/molecule.yml

...penstack/molecule/enable-everything/tests/test_default.py

ansible/roles/kolla-openstack/tasks/config.yml

ansible/roles/kolla-openstack/templates/placement.conf.j2

ansible/roles/kolla-openstack/vars/main.yml

doc/source/configuration/reference/kolla-ansible.rst

...s/notes/add-extended-placement-conf-70a4b9a318c1b555.yaml