Add framework to deploy user-defined containers on seed

ansible/group_vars/all/seed

ansible/roles/deploy-containers/defaults/main.yml

ansible/roles/deploy-containers/tasks/deploy.yml

ansible/roles/deploy-containers/tasks/main.yml

ansible/seed-deploy-containers.yml

doc/source/configuration/index.rst

doc/source/configuration/seed-custom-containers.rst

doc/source/deployment.rst

etc/kayobe/seed.yml

kayobe/cli/commands.py

kayobe/tests/unit/cli/test_commands.py

releasenotes/notes/deploy_containers-4199127a91f29be0.yaml