Get usage by subscription

curl --request POST \
  --url https://api.cloud.flexprice.io/v1/subscriptions/usage \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "subscription_id": "123",
  "end_time": "2024-03-20T00:00:00Z",
  "lifetime_usage": false,
  "start_time": "2024-03-13T00:00:00Z"
}
'

{
  "amount": 123,
  "charges": [
    {
      "amount": 123,
      "currency": "<string>",
      "display_amount": "<string>",
      "filter_values": {},
      "is_overage": true,
      "meter_display_name": "<string>",
      "meter_id": "<string>",
      "overage_factor": 123,
      "price": {
        "amount": 123,
        "billing_cadence": "RECURRING",
        "billing_model": "FLAT_FEE",
        "billing_period": "MONTHLY",
        "billing_period_count": 123,
        "conversion_rate": 123,
        "created_at": "<string>",
        "created_by": "<string>",
        "currency": "<string>",
        "description": "<string>",
        "display_amount": "<string>",
        "display_price_unit_amount": "<string>",
        "end_date": "<string>",
        "entity_id": "<string>",
        "entity_type": "PLAN",
        "environment_id": "<string>",
        "group_id": "<string>",
        "id": "<string>",
        "invoice_cadence": "ARREAR",
        "lookup_key": "<string>",
        "metadata": {},
        "meter_id": "<string>",
        "parent_price_id": "<string>",
        "price_unit": "<string>",
        "price_unit_amount": 123,
        "price_unit_id": "<string>",
        "price_unit_tiers": [
          {
            "flat_amount": 123,
            "unit_amount": 123,
            "up_to": 123
          }
        ],
        "price_unit_type": "FIAT",
        "start_date": "<string>",
        "status": "published",
        "tenant_id": "<string>",
        "tier_mode": "VOLUME",
        "tiers": [
          {
            "flat_amount": 123,
            "unit_amount": 123,
            "up_to": 123
          }
        ],
        "transform_quantity": {
          "divide_by": 123,
          "round": "<string>"
        },
        "trial_period": 123,
        "type": "USAGE",
        "updated_at": "<string>",
        "updated_by": "<string>"
      },
      "quantity": 123
    }
  ],
  "commitment_amount": 123,
  "commitment_utilized": 123,
  "currency": "<string>",
  "display_amount": "<string>",
  "end_time": "<string>",
  "has_overage": true,
  "overage_amount": 123,
  "overage_factor": 123,
  "start_time": "<string>"
}