Add site boundary meter consent

curl --request POST \
  --url https://api-sandbox.axle.energy/entities/site/{site_id}/meter-consent \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "gave_boundary_meter_consent_at": "2023-11-07T05:31:56Z"
}
'

{
  "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "mpan": "<string>",
  "postcode": "<string>",
  "address": "<string>",
  "asset_ids": [],
  "markets": [
    "cm"
  ],
  "dispatch_methods": [
    "cm_infrequent_dispatch"
  ],
  "tariff": {
    "tariff_type": "single_rate",
    "tariff_cheap_start_time": "<string>",
    "tariff_cheap_end_time": "<string>"
  },
  "gave_boundary_meter_consent_at": "2023-11-07T05:31:56Z"
}