stringifyNum doesn't stringify aggregates or ids

[sordina]

Enabling the "stringifyNum" option only seems to stringify direct column references to normal Num values.

Chinook example query:

{ tracks(limit:1) { unit_price }
  tracks_aggregate {
    aggregate { sum { unit_price } } } }

Response:

{
  "data": {
    "tracks": [
      {  "unit_price": "0.99"  }  ],
    "tracks_aggregate": {
      "aggregate": {
        "sum": {
          "unit_price": 3680.97  }  }  }  } }

Expected Response:

{
  "data": {
    "tracks": [
      {  "unit_price": "0.99"  }  ],
    "tracks_aggregate": {
      "aggregate": {
        "sum": {
          "unit_price": "3680.97"  }  }  }  } }