application credential renewal

[Francesco Maria Cultrera]

Actually, Openstack Ansible modules does not provide any module to manage application credentials and, unfortunately, it is not possible to use the `openstack.cloud.resource` since it requires CRUD operations, but application credentials are immutable and it does not have an `update` function. I think a new module is needed and it can be one specific for an application credential management OR one to manage non CRUD resources.

Example use case on serverfault: https://serverfault.com/questions/1144538/ansible-openstack-get-update-application-credentials