Support custom Ansible configuration

Tuning Ansible is typically done by customising configuration in
ansible.cfg. Currently Kayobe adheres to the standard locations for
Ansible configuration [1].

This change allows custom Ansible configuration files stored in the
kayobe-config repository to be used for execution of Kayobe and Kolla
Ansible playbooks.

[1] https://docs.ansible.com/ansible/latest/reference_appendices/config.html#ansible-configuration-settings-locations

Change-Id: Iab2021b8e88b5a3a2b0f8583f1246ab2c83670e5
Story: 2007494
Task: 39219