Save employees

Example request

{
  "data": [
    {
      "id": "emp_12345",
      "userId": "usr_67890",
      "email": "employee@example.com",
      "firstName": "John",
      "lastName": "Doe",
      "billableRate": 150,
      "ownershipPercentage": 25.5,
      "status": "ACTIVE",
      "customData": {
        "internal_key": "some_internal_key",
        "some_other_field": 23434
      }
    }
  ]
}