Add ability to view headers exchange structure

[jakauppila]

One of our systems heavily utilize headers-type exchanges which has hundreds of bindings on just a few exchanges which determine which queues messages get routed to. When visualizing that definition as-is it displays pretty flat, this is the result:

[jakauppila]

Here is a super simple example of a headers definition:

{
  "vhosts": [{
    "name": "contoso"
  }],
  "queues": [{
    "name": "MyQueue",
    "durable": true,
    "auto_delete": false,
    "arguments": {}
  }],
  "exchanges": [{
    "name": "MyExchange",
    "type": "headers",
    "durable": true,
    "auto_delete": false,
    "internal": false,
    "arguments": {}
  }],
  "bindings": [{
    "source": "MyExchange",
    "destination": "MyQueue",
    "destination_type": "queue",
    "routing_key": "",
    "arguments": {
      "operation": "EVENTA"
    }
  }]
}