add user totalSales and totalOrders

[alexcos20]

Closes #311

query{
  users{
    id,
    totalSales,
    totalOrders
  }
}

=>

{
  "data": {
    "users": [
      {
        "id": "0x02354a1f160a3fd7ac8b02ee91f04104440b28e7",
        "totalOrders": "0",
        "totalSales": "0"
      },
      {
        "id": "0x312213d6f6b5fcf9f56b7b8946a6c727bf4bc21f",
        "totalOrders": "2",
        "totalSales": "0"
      },
      {
        "id": "0x91eb42b164664cb28a09b0cf9651b404ee105afa",
        "totalOrders": "0",
        "totalSales": "0"
      },
      {
        "id": "0xa78deb2fa79463945c247991075e2a0e98ba7a09",
        "totalOrders": "0",
        "totalSales": "0"
      },
      {
        "id": "0xbb0911124e680d65358ac46c5404d4df01f03e80",
        "totalOrders": "0",
        "totalSales": "0"
      },
      {
        "id": "0xbe5449a6a97ad46c8558a3356267ee5d2731ab5e",
        "totalOrders": "1",
        "totalSales": "0"
      },
      {
        "id": "0xe2dd09d719da89e5a3d0f2549c7e24566e947260",
        "totalOrders": "0",
        "totalSales": "3"
      }
    ]
  }
}