Add support for Nornir

[dgarros]

Environment

• schema-enforcer version: 0.1.1

Proposed Functionality

Add a nornir command, similar to the ansible command
Since Nornir doesn't have a CLI nor does it always has a single inventory file, the interface will need to be different but the use case is similar.

Use Case

The use case is to be able to validate the hostvars generated by a Nornir inventory for each host, in a similar way than what we are doing today for Ansible.