Implement get_box_ip

[arpadszasz]

User story

Following the synopsis of the Rex::Commands::Box module and trying to get the IP address of a KVM box using get_box($_->{name})->{ip} results in an undef value.

The info for the KVM box does not include a hash key called ip, and even the primary NICs IP address seems to be empty:

'ens16_ip' => '',

Describe the solution you would like

There seems to already be a way to get the IP address across virtualization types using Rex::Box::Base::ip() which can be leveraged to provide a get_box_ip function.

Additional context

My fork contains an implementation of the get_box_ip function in the feature/get-box-ip branch (relevant commit: arpadszasz@0aecd52)