List external models

Example response

{
  "models": [
    {
      "id": "ethereum.beacon_blocks",
      "database": "ethereum",
      "table": "beacon_blocks",
      "description": "Beacon chain blocks from production cluster",
      "interval": {
        "type": "slot"
      },
      "cache": {
        "incremental_scan_interval": "10s",
        "full_scan_interval": "1h"
      },
      "lag": 10
    }
  ]
}