ci: setup molecule test for nic

[btravouillon]

Add molecule tests for role nic.
Add the tag molecule-notest to the modprobe tasks to avoid issues in the Docker containers. These modules are not required to test the role.

One test fails with ip4_multi using the example from the readme:

          - interface: multi0
            ip4_multi:
              - 172.16.0.2/16
              - 172.16.0.3/16
              - 192.168.1.117/24

Ansible skips the template task Set NIC configuration when ip4 is not defined, thus this interface is not configured. This might be a bug in the task, or an error in the documentation. @oxedions @johnnykeats please tell me if you need me to fix the task or the documentation.

I also fixed a condition where vlan was not considered as a boolean in task Load VLAN module if needed. (task was not skipped with vlan: False)