fix: #143, #174, #175

[soedirgo]

#143 and #175 are interrelated (they change the /query response format), so I decided to consolidate the fixes into 1 PR.

Fixes #174

dates, timestamps, and timestamptzs are no longer converted to JS Dates.

date before: "2020-01-01T00:00:00.000Z"

date after: "2020-01-01"

Fixes #143

Queries w/ multiple statements now return results from all statements instead of returning an empty list.

select 1 as a; select 2 as b before:

[]

select 1 as a; select 2 as b after:

[
  {
    "columns": [
      "a"
    ],
    "rows": [
      [
        1
      ]
    ]
  },
  {
    "columns": [
      "b"
    ],
    "rows": [
      [
        2
      ]
    ]
  }
]

Fixes #175

Columns with the same alias now works, but this required a breaking change in the response format.

select 1 as x, 2 as x before:

[
  {
    "x": 2
  }
]

select 1 as x, 2 as x after:

[
  {
    "columns": [
      "x",
      "x"
    ],
    "rows": [
      [
        1,
        2
      ]
    ]
  }
]

Additional notes

Previously, the response is a list of rows, but now that we support multi-statement queries, the response is a list of query results. In other words:

Type of response before: Record<string, unknown>[]
Type of response after: { columns: string[]; rows: unknown[][] }[]

[soedirgo]

In hindsight, I wonder if this would require a lot of refactors in Studio. If there are a lot of call sites that rely on the old response format, we can expose the "arrayMode" as a new endpoint instead.