Feature/add new worker nodes by using ova

[fperearodriguez]

Adding a new role to create additional worker/infra nodes using an OVA template.

About the new role:

• The role's name is vsphere_vm_new_nodes.
• A new playbook file has been created to execute it. The file name is new_worker_ova.yml.
• This new playbook file uses a new cluster file that should be named _{{ clusters_folder }}/{{ cluster }}additional_nodes_ova.yaml.
• A new section to explain the role usage has been added to the main README.
• Additional information has been added to the cluster file to explain each parameter of this file.
• Since this role works with infra nodes, it has been configured to label the nodes as infra or ODF (in this case, with the specific label and taint).