Add service for event and integration with Prefect event

[dgarros]

Initial integration of Infrahub events with prefect event

To avoid having to define/send event twice, I've introduced a new event service that will automatically send event to the message bus and to prefect.
This PR also introduces a new InfrahubEvent dataclass which support both formats: internal bus and prefect

For now I've only implemented the node mutated event for testing.

I'm still exploring how events are working in prefect and what is the best way to integrate with them.
in prefect an event must have be associated with a resource and can have multiple related resources.
Both resource and related resources are defined as a dictionary of key: value pair with the following constraints

• resource must include at least prefect.resource.id
• related resources must include at least prefect.resource.id and prefect.resource.role

below is the payload of the event generated after creating a new node in prefect

{
  "id": "7388044d-2faa-4d83-ba03-7225bf5ea276",
  "event": "infrahub.node.added",
  "occurred": "2024-09-29T15:39:22.972Z",
  "payload": {
    "id": "17f9c134-2f6a-c4d3-38ed-c517bcdee703",
    "name": {
      "id": "17f9c134-4ef8-faa3-38e7-c513cc3cb884",
      "owner": null,
      "value": "BLUE",
      "source": null,
      "__typename": "Text",
      "is_visible": true,
      "is_protected": false
    },
    "type": "BuiltinTag",
    "__typename": "BuiltinTag",
    "description": {
      "id": "17f9c134-4ef9-be70-38e2-c51048ea7d81",
      "owner": null,
      "source": null,
      "__typename": "Text",
      "is_visible": true,
      "is_protected": false
    },
    "display_label": "BLUE"
  },
  "received": "2024-09-29T15:39:22.994Z",
  "related": [
    {
      "prefect.resource.id": "infrahub.request.10e771ce781f4314acbf2307029a42ba",
      "prefect.resource.role": "request"
    },
    {
      "prefect.resource.id": "infrahub.source.80af6c07-61f4-461c-84db-ed85ff874daa",
      "prefect.resource.role": "event_source"
    },
    {
      "prefect.resource.id": "infrahub.branch",
      "prefect.resource.name": "main",
      "prefect.resource.role": "branch"
    }
  ],
  "resource": {
    "infrahub.node.kind": "BuiltinTag",
    "prefect.resource.id": "infrahub.node.17f9c134-2f6a-c4d3-38ed-c517bcdee703",
    "infrahub.node.action": "added"
  }
}

[ogenstad]

It might have a bit limiting previously to only have kind but I think the addition of namespace here gets a bit weird if we keep kind. We should either just leave it as "kind" or remove kind if we have "name" and "namespace.

[dgarros]

I removed it for now, we can revisit that later but having just the kind is not enough in my perspective if we need to do some filtering

[ogenstad]

This looks a bit problematic, is there an async version of emit_event?

[dgarros]

Not that I could find quickly but as far as I understand they are sending the event in a non blocking way. I'm planning to dive deeper into it soon.
We may have to create our own function to send the event but for now since we are sending the events in a background task I don't think it will make a big different

[ogenstad]

Ah right the background tasks are run in a separate thread regardless. But we'll have to keep it in mind if used elsewhere, though if Prefects emit_event does the same it should be fine.