Add an option Show Neighbors

[antoinekh]

Hi,

I really like the UI of this plugin but for us a key feature is missing: show neighbors.
This feature makes it easy to see where a device is connected and all it's neighbors.
This is almost the same need that #42

This feature exist in netbox-topology-views

https://github.com/netbox-community/netbox-topology-views/blob/25fdcb6cf4fde1416f2f3f2c06e66f956b4436d6/netbox_topology_views/views.py#L377

It would be really nice if this could be added in the future.