Default events configuration and unrelated events back up

[Rossb0b]

Add a default config for events subscribers (publishers?), to avoid loss of events when there isn't related incomer(s).

• The event list isn't static. If an unrecorded event does exist, add it.
• The Subscriber list isn't static. If an unrecorded subscriber does exist, add it.
• By default, if an event is unrecorded or there aren't subscribers, back up the event.
  • no expiration delay for keys, threshold on number of keys, warning on number of keys at specifics threshold. (Needs of a manual interaction to avoid event loss)

{
  "foo-event": {
    "subscribers": [
      {
        "name": "foo",
        "horizontalScale": true
      },
      {
        "name": "bar"
      }
    ]
  },
  "bar-event": {
    "subscribers": []
  }
}

[Rossb0b]

Add number of replicas for API(s) instances so events that must scale, must be based on this number of replicas ?