Set up metric collection with prometheus and telegraf as the SNMP proxy.

NetBox config context should contain the lists `prometheus_hosts` and `snmp_hosts` with job definitions. Each entry should define `name` and `nb_filter` user to query hosts from NetBox. For example:

    {
        "prometheus_hosts": [
            {
                "name": "classroom",
                "nb_filter": "role=desktop-computer status=active location=classroom"
            }
        ],
        "snmp_hosts": [
            {
                "name": "switch",
                "nb_filter": "role=switch name__isw=sw- status=active status=staged status=planned"
            }
        ]
    }