Push events for an LLM Observability experiment

Example request

{
  "data": {
    "attributes": {
      "metrics": [
        {
          "assessment": "pass",
          "label": "faithfulness",
          "metric_type": "score",
          "span_id": "span-7a1b2c3d",
          "timestamp_ms": 1705314600000
        }
      ],
      "spans": [
        {
          "dataset_id": "9f64e5c7-dc5a-45c8-a17c-1b85f0bec97d",
          "duration": 1500000000,
          "meta": {
            "error": {
              "message": "Model response timed out",
              "stack": "Traceback (most recent call last):\n  File \"main.py\", line 10, in <module>\n    response = model.generate(input)\n  File \"model.py\", line 45, in generate\n    raise TimeoutError(\"Model response timed out\")\nTimeoutError: Model response timed out",
              "type": "TimeoutError"
            }
          },
          "name": "llm_call",
          "project_id": "a33671aa-24fd-4dcd-9b33-a8ec7dde7751",
          "span_id": "span-7a1b2c3d",
          "start_ns": 1705314600000000000,
          "status": "ok",
          "trace_id": "abc123def456"
        }
      ]
    },
    "type": "events"
  }
}