Story: 2008170
Task: 40925

Change-Id: I3014983f481a5dca7c93e140b3e10caa5d537669

Kayobe generates a host_vars file for each host in the Kolla Ansible
inventory. These contain network interfaces and other host-specific
things. Currently this is done by iterating over all hosts, which does
not scale well with a large number of hosts.

This change extracts the host vars generation into a separate role, and
executes it in a play targeted at all hosts, with delegate_to:
localhost. This ensures that host variable files are generated in
parallel.

Story: 2007993
Task: 40629

Change-Id: Iae75e17024adee9c2874c14d3ed36f4c87ba48d7

Adds support for HTTP basic authentication with the Docker registry.

The kolla docker registry password is now written to passwords.yml.

Change-Id: Ie6e854a66a6660d4e02771fe2b5dd97af814194d
Story: 2007952
Task: 40429

The variables in yum.yml and yum-cron.yml were deprecated in Ussuri.
This patch removes them, and updates the defaults in dnf.yml.

Story: 2008160
Task: 40906

Change-Id: I97cc98dd2ff726e5885fefcab17f17796d9fd453

This allows us to add configuration scenarios.

Change-Id: Id636f78c61237fb27fa65fa3d4b3fc1a4cf0ba6a
Story: 2004360
Task: 40777