feat(controlplane): add extra info to discovery endpoint

[migmartri]

The main goal of this patch is to add additional information to the discovery endpoint when the nodes are attestations kinds.

So now, the metadata struct contains the team, project and organization name. To achieve this I've added the organization to the attested object metadata as well.

{
   "digest": "sha256:05251995ddb3380ce3a719d374a18cc9ab5e2a48852ee96b0361ef329447b801",
   "kind": "ATTESTATION",
   "downloadable": true,
   "public": false,
   "createdAt": "2024-03-29T21:51:12.852033Z",
   "references": [
      {
         "digest": "sha1:d6e16f863e47c0a75e812faa870c27d5c600faa4",
         "kind": "GIT_HEAD_COMMIT",
         "downloadable": false,
         "public": false,
         "createdAt": "2024-03-29T21:29:40.092477Z",
         "references": []
      }
   ],
   "metadata": {
      "name": "foo-b2az",
      "organization": "wizardly-mccarthy-3002",
      "project": "bar",
      "team": "my-team"
   }
}

refs #498

[danlishka]

LGTM