[ADDED] Option to include subscription details in monitoring responses

[matthiashanel]

added sub=detail option to routez/connz.
When specified will include subscriptions_list_detail instead.
I would have liked to change the type of subscriptions_list from []string to []interface{} and not have subscriptions_list_detail, but that is part of the interface used by embedded server.

Applies to routez and connz and closed connections.
with detail

{
  "server_id": "NDVNBYWHR7OZFDDVLNAHFK5PLRTBLENHSNMRV5WBSFAF6W3E67PCLC6A",
  "now": "2020-03-20T17:00:12.399586-04:00",
  "num_connections": 1,
  "total": 1,
  "offset": 0,
  "limit": 1024,
  "connections": [
    {
      "cid": 2,
      "ip": "127.0.0.1",
      "port": 49722,
      "start": "2020-03-20T16:59:57.558987-04:00",
      "last_activity": "2020-03-20T17:00:05.690868-04:00",
      "uptime": "14s",
      "idle": "6s",
      "pending_bytes": 0,
      "in_msgs": 0,
      "out_msgs": 0,
      "in_bytes": 0,
      "out_bytes": 0,
      "subscriptions": 1,
      "subscriptions_list_detail": [
        {
          "subject": "foo",
          "qgroup": "queue",
          "sid": "5",
          "msgs": 0,
          "cid": 2
        }
      ]
    }
  ]
}%

without

curl "http://localhost:8080/connz?subs=1"
{
  "server_id": "NDVNBYWHR7OZFDDVLNAHFK5PLRTBLENHSNMRV5WBSFAF6W3E67PCLC6A",
  "now": "2020-03-20T17:00:08.310969-04:00",
  "num_connections": 1,
  "total": 1,
  "offset": 0,
  "limit": 1024,
  "connections": [
    {
      "cid": 2,
      "ip": "127.0.0.1",
      "port": 49722,
      "start": "2020-03-20T16:59:57.558987-04:00",
      "last_activity": "2020-03-20T17:00:05.690868-04:00",
      "uptime": "10s",
      "idle": "2s",
      "pending_bytes": 0,
      "in_msgs": 0,
      "out_msgs": 0,
      "in_bytes": 0,
      "out_bytes": 0,
      "subscriptions": 1,
      "subscriptions_list": [
        "foo"
      ]
    }
  ]
}%  

[kozlovic]

No need for public function and maybe some refactor to reduce duplicated code.

[kozlovic]

I would have made it a []*SubDetail in case we ever need to sort those (since []SubDetail would force move of SubDetail struct inside the array), but I see that we also use []SubDetail in subz, so...

[kozlovic]

Comment about the copy of routez option was not addressed?

[kozlovic]

LGTM

[matthiashanel]

After discussion, changed the logic to avoid the copy alltogether.

[kozlovic]

LGTM