Send metrics in bulk

Example request

{
  "applications": [
    {
      "connectVia": [
        {
          "appName": "unleash-edge",
          "instanceId": "edge-pod-bghzv5"
        }
      ],
      "appName": "Ingress load balancer",
      "environment": "development",
      "instanceId": "application-name-dacb1234",
      "interval": 10,
      "started": "2023-07-27T11:23:44Z",
      "strategies": [
        "standard",
        "gradualRollout"
      ],
      "projects": [
        "projectA",
        "projectB"
      ],
      "sdkVersion": "unleash-client-java:8.0.0",
      "sdkType": "backend"
    }
  ],
  "metrics": [
    {
      "featureName": "my.special.feature",
      "appName": "accounting",
      "environment": "development",
      "timestamp": "2023-07-27T11:23:44Z",
      "yes": 974,
      "no": 50,
      "variants": {
        "variantA": 15,
        "variantB": 25,
        "variantC": 5
      }
    }
  ],
  "impactMetrics": [
    {
      "name": "my-counter",
      "help": "Counts the number of operations",
      "type": "counter",
      "samples": [
        {
          "value": 10,
          "labels": {
            "application": "my-app",
            "environment": "production"
          }
        }
      ]
    }
  ]
}